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and diversified group of the Arachnida; about zooo species are known. No noteworthy fossil spiders are known; the best-preserved are in amber of ôligocene age. Protolycosa and Arthrolycosa occur in the Carboniferous. Morphologically, the spiders are remarkable for the concentration and specialization of their structure, which is accompanied with high physiological efficiency. The larger species of Bird's Nest Spiders (Avicularia), the opisthosoma of which is as large as a bantam's egg, undoubtedly attack young birds, and M'Cook gives an account of the capture in its web by an ordina

house spider of a small mouse. The "retrovert" or bent-bac

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first pair of appendages is provided with a poison gland opening on the £ or terminal segment. Spiders form at least two kinds of constructions-snares for the capture of £ and nests for the preservation of the young. The latter are only formed by the female, which is a larger and more powerful animal than the male. Like the scorpions the spiders have a special tendency to cannibalism, and accordingly the male, in approaching the female for the purpose of fertilizing her is liable to be fallen upon and sucked dry by the object of his attentions. The sperm is removed by the male from the genital aperture into a special receptacle on the terminal segment

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of the 2nd prosomatic appendage. Thus held out at some distance from the body, it is cautiously advanced by the male spider to the genital aperture of the female. For an account of the courtship and dancing of spiders, of their webs and floating lines, the reader is referred to the works of M'Cook (30) and the Peckhams (31), whilst an excellent account of the nests of trap-door £ is given by Moggridge (32). References to systematic works will also be found at the end of this article (33). Order4. Palpigradi-Microthelyphonidae (see fig. £ covered above by three plates, a larger representing the dorsal elements of the first four somites, and two smaller representing the dorsal elements of the 5th and 6th. Its ventral surface provided with one prosternal, two mesosternal and one metasternal plate. Appendages of 1st pair consisting of three segments, completely chelate, without poison gland; of 2nd pair slender, leg-like, tipped with three claws, the basal segment without sterno-coxal process taking no share in mastication, and

widely separated from its fellow of the opposite side; 3rd, 4th, 5th and 6th appendages similar inform to the 2nd and to each #. Proboscisfree, not supported from below by either the prosternum or the basal segments of the £ of the 2nd pair. Opisthosoma consisting of only ten somites, which have no tergal and sternal elements, the prae-genital somite contracted to form a "waist," as in the Pedipalpi; the last three narrowed to form a

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111111VVVlson Opisthosoma
Pre-

Fig. 65.-Koenenia mirabilis, Grassi, one of the Palpigradi.

A, Ventral view of prosoma and B, Dorsal view. I to VI, proof anterior region of opistho- somatic appendages; 1 opisth, soma with the appendages cut genital somite (first opisthosooff near the base; a and b, ... matic somite). prosternites; c, mesosternite: C, Lateral view, I to VI, proand d, metasternite of the somatic appendages; a b,c, prosoma; f, ventral surface the three tergal £, of the of the prae-genital somite; prosoma; prae-gen, the prae

g, sternute the genital genital somite; 1 to 10, the somite (first opisthosomatic ten,somites of the opisthosoma. somite). D, Chelicera.

(Original drawing by Pocock and Pickard-Cambridge, after Hansen and Sörensen.) caudal support for the many-jointed #" telson, as in the

Urotricha. Respiratory organs atrophi £: oeneniidae £ Remarks-An extremely remarkable minute form originally described by Grassi (34) from Sicily, and since further £ by Hansen (35). Recently the genus has been found in Texas, U.S.A. Only one genus of the order is known. Order 5. Solifugae=Mycetophorae (see figs. 66 to 69).-Dorsal area of prosoma covered with three distinct plates, two smaller representing the terga of the 5th and 6th somites, and a larger representing those of the anterior four somites, although the reduced terga of the 3rd and 4th are traceable behind the larger plate. The latter bears a pair of median eyes and obsolete lateral eyes on each side. Sternal elements of prosoma, almost entirely absent, traces of a prosternum and metasternum alone remaining. Rostrum free, not supported by either the prosternum or the basal segments of the appendages. Appendages of 1st pair large, chelate, bisegmented, articulated to the sides of the head-shield; £ of 2nd pair simple, iform, with protrusible (? suctorial) organ, and no claws at the tip; their basal segments united in the middle line and furnished with sterno-coxal process. Remaining pairs of appendages with their basal segments immovably fixed to the *''' similar inform, the posterior three pairs furnished with two claws supported on long stalks; the basal segments of the 6th pair bearin five pairs of tactile sensory organs or malleoli. The prae-genita somite is suppressed. Opisthosoma composed of ten-somites. Respiratory organs tracheal, opening upon the ventral surface of the 2nd and 3rd, and sometimes also of the 4th somite of the opisthosoma. A supplementary pair of tracheae opening behind the basal segment of the 4th appendage of the prosoma. (? Intromittent organ of male lodged on the dorsal side of the 1st pair of prosomatic #"#! Families-Hexisopodidae. (Hevisopus). Solpugidae (Solpura. Rhagodes). Galeodidae (Galeodes)

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Remarks.-These most strange-looking Arachnids occur in warmer temperate, and tropical regions of Asia, Africa and America. Their £ has not n studied, as yet, by means of freshly-killed material, and is imperfectly known, though the presence of the coxal

Fig. 66.—Galeodes sp., one of the Solifugae. Ventral view to show legs and somites. I to VI, The six leg-bearing

somites of the prosoma. opisth 1, First or genital

somite of the opistho

Soma- ge, Site of the genital anerture.

st, Thoracic tracheal

aperture. P, £ tracheal aperture of the opisthosoma in somite 2 of the opistho

SOIT11, P, Tracheal aperture, in somite 3 of the opistho

Sonnaa, Anus. (From Lankester." Limulus and Arachnid.")

QFIG._67-Galeodes sp., one." FIG.68.-Galeodes sp., one of the of the Solifugae. Ventral view Solifugae. Dorsal view. with the appendages cut of 1 to vi, Bases of the prosomatic at the appendages. I to VI, Prosomatic append-o, Eyes. 21-5. - a, Lateral region of the cephalic plate s, Prosomatic stigma or aper-" to which the first pair of appendture of the tracheal system. ages are articulated. 1, First opisthosomatic ster, b, Cephalic plate with median eye. nite covering the genital c, Dorsal element of somites bearing aperture g. - - third and fourth pairs of append2, Second opisthosomatic ster-, ages. nite covering the second d. Second plate of the prosoma with pair of tracheal apertures fifth pair of appendages. e, Third or £ plate of the prosoma beneath which the sixth - pair of legs is articulated. he tenth opisthosomatic 1, 2, 9, 10, First, second, ninth and somite. tenth somites of the opisthosoma. an, The anal aperture. an, Anus.

(original by Pickard-Cambridge and Pocock.)

sp1. sp2, The third pair of tracheal a Dertures. 10,

(Original)

glands was determined by Macleod in 1884. The proportionately enormous chelae (chelicerae) of the first pair of appendages are not provided with poison glands; their bite is not venomous.

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Conn , at least in many cases, of eleven somites, the 11th 1 three minute and forming a - somite very small, often, hidden within the 10th. Respi y I of Thelyph forming : #: organs in the form of tracheal tubes opening by a pair of stigmata || spiracles in the prosoma above the base of the fifth appendage On

in the 2nd and 3rd somites of the opisthosoma. Intromittent organ of male beneath sternum of the 1st somite of the opisthosoma.

Sub-order a Panctenodactyli-Dorsal plate of prosoma (carapace) narrowed in front; the appendages of the 1st pair small, much narrower, taken together, than the posterior border of the carapace. Serrula on movable digit of appendages of 1st pair fixed throughout its length, and broader at its proximal than at its distal end; the immovable digit with an external process.

Family-Cheliferidae (Cheifer (figs.70,71,72), Chiridium). - Garypidae (Garypus).

Sub-order b. Hemictenodactyli-Dorsal plate of prosoma scarcel narrowed in front; the appendages of the 1st pair large, not £ narrower, taken together, than the posterior border of the carapace a prae-gen 1 2 3 r | 1 ||

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I to VI, Basal segments of the 2, 3, 1o, The second, third and six prosomatic appendages. tenth somites of the opisthoo, Eyes. Sonna. prae-gen, Tergite of the prae- 11, The minute eleventh somite; nital somite. [somite. an, The anus. 1. 8', or first opisthosomatic (Original)

The serrula or the movable digit free at its distal end, narrowed at the base, no external lamina on the immovable digit. Family—Obisiidae (Obisium, Pseudobisium) - Chthoniidae (Chthonius, Tridenchthonius). Remarks.-The book-scorpions-so called because they were, in old times, found not unfrequently in libraries—are found in rotten wood and under stones. The similarity of the form of their appendages to those of the scorpions suggests that they area degenerate group derived from the latter, but the large size of the prae-genital somite in them would indicate a connexion with forms preceding the scorpions. Reference to literature (37). Order 7. Podogona =Ricinulei (see figs. 73 to 76).--Dorsal area of prosoma furnished with two shields, a larger behind representing, probably, the tergal elements of the somites, and a smaller in front, which is freely articulated to the former and folds over the

In soft . ". *

c drs FIG. 73--Cryptostemma, Karschii, one of the Podogona view of male. ill to VI, The third, fourth, fifth and sixth appendages of the ro50nna, an, Orifice within which the caudal G, ': (hinged) sclerite (so- segments are withdrawn. called hood) overhanging the E, Extremity of the fifth appendfirst pair of appendages. age of the male modified to 5, Fused terga of the prosoma subserve copulation. (Original drawing by Pocock and Pickard-Cambridge) d £ of the 1st pair. Ventral area without distinct sternal plates. Appendages of 1st pair, bi-segmented, completely chelate.

Dorsal

followed by the opisthosoma of four visiblesomites.

Appendages of 2nd pair, with their basal segments uniting in the £ line below the mouth, weakly chelate at apex. #: of 3rd, 4th, 5th and 6th pairs similar in form, their basal segme in contact in the middle line and immovably welded, exce of the £ pair, which have been pushed aside so that th the 2nd and 4th pairs are in contact with each other. A. membranous joint between the prosoma and the opisthosoma, the nerative aperture opening upon the ventral side of the membrane rae-genital somite suppressed; the opisthosma consisting of nine segments, whereof the first and second are almost suppressed and concealed within the joint between the prosoma and the opisthosoma; the following four large and manifest, and the remaining

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FIG. 74--Cryptostemma Karschii. anterior aspect of the prosoma with the “hood” removed. I to IV, first to fourth appendages of the prosoma: a, basal segment of the second pair of appendages meeting its fellow in the middle line (see fig. 75).

(Original drawing by Pocock and * Pickard-Cambridge.)

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traceable; the generative aperture thrust far forwards between the basal ments of the 6th appendages. . Prae-genital somite suppressed. Respiratory organs tracheal, opening by a pair of stig

mata situated immediately behind the basal segments of the 6th pair of appendages on what is probably the sternum of the 2nd :* somite and also in some cases upon the 5th segment of the

Intromittent organ of male lying within the £ orifice.

Sub-order a. Laniatores.-Orifice of foetid glands opening above the coxa of the 4th appendage, not raised upon a tubercle. Orifice of coxal gland situated just behind that of the foetid gland, Sternal

of prosoma long and narrow, with a distinct prosternal element

the mouth. Coxae of 4th, 5th and 6th appendages of 2nd pair, strong, usually prehensile ce covered by an operculum. leptidae (Gonolepies, Goniasoma). ntidae (Bianles). * * * lin. Oncopodidae (Oncopus, Peltinus).

( pTrioenonychidae ( £ Acumontia).

- alpatores-Orifice of foetid glands opening above the 3rd appendage, not raised upon a tubercle. Orifice of coxal situated

n ween the coxae of ' and 6th appendages. Sternal plate of prosoma usually short and wide, rarely longer than broad; with a larger or smaller prosternal element underlying

mouth. Coxae of 3rd, 4th, 5th and 6th appendages movable or immovable. Appendages of 2nd pair weak, pediform not prehensile. Genital orifice covered by an operculum. Families-Phalangiidae (Phalangium, Gagrella). Ischyropsalidae (Ischyropsalis, Taracus). Nemastomidae (Nemastoma). - - Trogulidae (Trogulus, Anelasmocephalus), Sub-order c. £ (Anepignathi).—Orifice of foetid glands opening on a tubercle situated near the lateral border of the carapace above the base of the 5th appendage. Orifice of coxal gland probably situated at base of coxa of 5th appendage; sternal late of prosoma minute or absent; no prosternal element underying the mouth. Coxae of 5th and 6th, and usually also of 4th appendages immovable. Appendages of 2nd pair weak, pediform, not prehensile. Genital orifice not covered by an operculum. Families-Sironidae (Siro, # - Stylocellidae (Stylocellus Remarks on the Opiliones.-These include the harvest-men, sometimes called also daddy-long-legs, with round undivided bodies and very long, easily-detached legs. The intromittent organs of the male are remarkable for their complexity and elaboration. The confluence of the regions of the body and the dislocation of apertures from their typical position are results of degeneration. The Opiliones seem to lead on from the Spiders to the Mites. Reference to literature (39). Apparently related to the Opiliones are two extinct groups, the Anthracomarti and Phalangiotarbi, which are not known to have survived the Carboniferous period. In the Anthracomarti the

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FIG. 77.—Stylocellus B sumatranus, one of the 1 Qpiliones; after Thorell. ---it Enlarged. -III A, Dorsal view; I to VI, ; "'V the six prosomatic appendages. E{I B, Ventral view of the prosoma and of the first somite of the opisthosoma, with the appendages. I to VI cut off at the base; a, tracheal D stigma; mx, maxillary processes of the coxae of the 3rd pair of appendages; g, genitalaperture. C, Ventral surface of the prosoma and opisthoso ma; a trach eal - stigma; b, last somite. £5% • E D, Lateral view of the art:--> \ 1st and 2nd pair of appendages. E, Lateral view of the whole body and two 1st appendages, show. ing the fusion of the dorsal elements of the prosoma into a single plate, and of those of the opisthosoma into an imperfectly segmented plate continuous with that of the prosoma. £ was movably articulated to the prosoma, and consisted of from eight to ten segments furnished with movable lateral plates, the anal segment being overlapped dorsally by a laminate expansion of the preceding segment. The carapace of the prosoma was unsegmented and often bore a pair of eyes. The appendages of the 2nd pair were slender and iform; those of the 3rd, 4th, 5th and 6th pairs were similar in form and ambulatory in function with their basal segments arranged round a sternal area as in the order Araneae. The best-known genera were Anthracomartus and Eophognus. n the Phalangiotarbi the appendages resembled those of the Anthracomarti, except that the basal segments of the last four pairs were usually approximated in the middle line leaving a long and narrow sternal area between; and the carapace of the prosoma was unsegmented. The prosoma and opisthosoma were broadly confluent and probably immovably welded together. The opisthosoma consisted of eight or nine segments, whereof the anterior five or six were very short in the dorsal region, and the posterior three exceptionally large with the anal orifice terminal. Several genera have been established, the best-characterized being Geraphognus and Architarbus. Order 9. Rhynchostomi = Acari (see fig. 78).-Degenerate Arachnids resembling the Opiliones in many structural points, but chiefly distinguishable from them # the following features:-The basal segments of the appendages of the 2nd pair are united in the middle line behind the mouth, those of the 3rd, 4th, 5th and 6th pairs are widely separated and not provided with sterno-coxal (maxillary) lobes, and take no share in mastication; the respiratory stigmata, when present, belong to the prosoma, and the primitive segmentation of the opisthosoma has entirely or almost entirely disappeared. Sub-order. G., Notostigmata.-Opisthosoma, consisting of ten segments defined by integumental grooves, each of the anterior four

of these furnished with a single pair of dorsally-placed spiracles or tracheal stigmata. Family—Opilioacaridae (Opilioacarus). Sub-order b. £ ument hard, strengthened by a continuously chitinized dorsal and ventral sclerite. Tracheae typically opening by stigmata situated in the articular sockets (acetabula) of the 3rd, 4th, 5th and 6th pairs of *# cs, Family-Oribatidae (Oribata, '', Hoplophora). Sub-order c. Metastigmata.-Integument mostly like that of the Cryptostigmata. Tracheae opening by a pair of stigmata situated above and behind the base of the# or 5th or 6th pair of appendages. Families-Gamasidae (Gamasus, Pteropius). Argasidae (A£ Ornithodoros). - Ixodidae (Ixodes, Rhipicephalus). Sub-order d. Prostigmata.-Integument soft, strengthened by special sclerites, those on the ventral surface of the prosoma apparently representing the basal segments of the legs embedded in the skin. Tracheae, except in the aquatic species in which they are atrophied, opening by a pair of stigmata situated close to or above the base of the appendages of the 1st pair (mandibles). Families-Trombidiidae (Trombidium, Tetranychus). Hydrachnidae (Hydrachna, Atax). Halacaridae (Halacarus, Leptognathus). Bdellidae (Bdella, Eupodes). Sub-order e. Astigmata.-Degenerate, mostly parasitic forms approaching the Prostigmata in the development of integumental

FIG.78.—Holothyrus nitidissimus, one of the Acari; after Thorell.

A, Lateral view with appendages III to VI removed, 1, plate covering the whole dorsal area, representing the fused tergal sclerites of the prosoma and opisthosoma; 2, similarly-formed ventral plate; 3, tracheal stigma.

B, Dorsal view of the same animal; II to VI, 2nd to 6th pairs of appendages. The 1st pair of appendages both in this and in C are retracted.

C, Ventral view of the same: II to VI as in B; a, genital orifice; b, anus; c, united basal segments of the second pair of appendages; d, basal segment of the 6th prosomatic appendage of the right side. The rest of the appendage, as also of app. III, IV and V, has been cut away.

: and the softness of the skin, but with the respiratory system absent. Families–Tyroglyphidae (Tyroglyphus, Rhizoglyphus). Sarcoptidae (Sarcoptes, Analges).

Sub-order f. Vermifornia.-Degenerate atracheate parasitic forms with the y produced posteriorly into an annulated caudal longation, and the 3rd, 4th, 5th and 6th pairs of appendages short and only three-jointed.

Family-Demodicidae (Demodex).

Sub-order g. £ atracheate gall mitesin which the # is produced posteriorly and annulated, as in Demodex, but in which the appendages of the 3rd and 4th pairs are long and normally segmented and those of the 5th and 6th pairs entirely absent.

£ (Eriophyes, Phyllocopies).

Remarks on the Rhynchostomi.—The Acari include a number of forms which are of importance and special interest on account of their parasitic habits. The ticks (Ixodes) are not only injurious as blood-suckers, but are now credited with carrying the germs of Texas cattle-fever, just as mosquitoes carry those of malaria. The itch-insect (Sarcoples scabiei) is a well-known human parasite, so minute that it was not discovered until the end of the 18th century, and “the itch" was treated medicinally as a rash. The female burrows in the epidermis much as the female trap-door spider burrows in turf in order to make a nest in which to rear her young. The male does not burrow, but wanders freely on the surface of the skin.

. Demodex folliculorum is also a common parasite of the sebaceous

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vol. viii., 1884; Pelseneer, "On the Coxal Glands of Mygale,” Proc. Zool. Soc., 1885; Tower, “The External Opening of the brick-red Glands of Limulus,” Zool. Anseiger, vol. xviii. p. 471, 1895. Entosternite:-Schimkewitsch," Bau und Entwick...des Endosternites der Arachniden,"Zool. Jahrb., Anal. £ Embryology: -Balfour," Development of the Araneina,” Q. J. Micr.Sci. vol.xx.. 1880; Kingsley, “The Embryology of Limulus,” Journ. Morphology, vols. vii. and viii.; Kishinouye, “ relopment of Araneina,” Journ. Coll: Sci., Univ. of Japan, vol. iv., 1890; Locy, “Development of Agelena,” Bull. Mus. Ilarvard, vol. xii., 1885; Metchnikoff, “Em# d. Scorpion." Zeit. wiss. Zool. vol. xxi., 1871; Idem, “Embryol. Chelifer." Zeit wiss. Zool. vol.xxi., 1871; Schimkewitsch, “Développement des Araignées,” Archives d. Biologie, vol. vi. 1887. Sense "#. “Sinne:game der Spinnen.” Arch. f. mikros. Anal. vol. xxvii. p. # 1886; Graber, “ Unicorneale Tracheaten Auge," Arch. f. mikr. Anat, vol. xvii., 1879; Grenacher, Gehörorgane der Arthropoden (Göttingen, 1879); Kishinouye," Lateral £ of Spiders.” Zool. Anz. vol. xiv. p. 381, 1891; Purcell," Phalangiden Augen," Zool. Anzeiger, vol. xv. p. 461. General works on Arachnida:-Blanchard, “Les Arachnides" in £" du régne animal; Gaubert, “Recherches sur les Arachnides "Ann. Sci. Nai. (7) vol. xiii., 1892:"Koch Č. p. Arachniden (16 vols., Nuremberg, 1831-1848); Koch, Keyserling and Sörensen, Die Arachniden Australiens (Nuremberg, 18 1-1899): Pocock, Arachnida of British India (London, 1900); Idem, “On African Arachnida," in Proc. Zool. Soc., and Ann. and Mag. Nat. Hist., 1897-1900; Simon, Les Arachnides de la France (7 vols., Paris, 1874-1881); Thorell, “Arachnida from the Oriental Region,” Ann. Mus. Genova, 1877-1899. (E. R. L.) ARAD, or O-ARAD, a town of Hungary, capital of the county of the same name, 159 m. S.E. of Budapest by rail. Pop. (1900) 53,903. It is situated on the right bank of the river Maros, and consists of the inner town and five suburbs. Arad is a modernbuilt town,and contains many handsome private and public buildings, including a cathedral. It is the seat of a Greek-Orthodox bishop, and possesses a Greek-Orthodox theological seminary, two training schools for teachers—one Hungarian, and the other Rumanian—and a conservatoire for music. The town played an important part in the Hungarian revolution of 1848-49, and possesses a museum containing relics of this war of independence. One of the public squares contains a martyrs' monument, erected in memory of the thirteen Hungarian generals shot here on the 6th of October 1849, by order of the Austrian general Haynau. It consists of a colossal figure of

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