almost creative influence in framing or modifying animal structures which many imagine they have; for here are before us a crowd of animals whose soft bodies, it will be allowed, are as susceptible of changes, or of being moulded to one type, as any animals can be, and the uniformity of whose nervous system seems to prove that their faculties and desires are much on a par; yet, if we select any large family from among them, we shall find them living in the same seas, and in the same depths, and in the same latitudes, and on the same food, and all breathing the same air; but, so far from showing a perfect agreement in their exterior organs, on which these causes are said to operate so efficiently, we find all is diverse, whether we look to the position, the form, or the structure of the organs. These are now, my friend, such as they were when the creatures came into existence from Infinite Wisdom, perfect, and complete, and immutable, and, notwithstanding all their variations, ever suited with special adaptation to the element and the place they were foreordained to inhabit. "Their forms are His special invention and construction, and their principle of life is also His special and communicated gift," is the just conclusion of a historian eminently distinguished for his learning, his good sense, and his piety.*

Now, the distinction which has been drawn between the Mollusca with lungs and gills, however anatomically correct, is not always physiologically true; for although I am not cognisant of any pulmoniferous species that can breathe water, or ever does so voluntarily, yet there are many branchiferous ones that can and do respire the uncombined air. A great number of bivalves are alternately submerged and exposed to the air, according to the fluctuations of the tide; but then the concavity of the lower valve enables the animal always to retain some moisture around its gills, and I believe they do not open their shells freely unless when covered with water. The Octopi of the cuttlefish tribe are said to come ashore frequently, and live among the rocks for days together; and the Pteropoda and the naked Gasterópoda in general love to swim at the surface in calm weather, particularly at the time of sunset, apparently to enjoy the respiration of a lighter and more oxygenated medium. There are other Gasterópoda with gills which pass so large a portion of their term of life

*Mr. Sharon Turner. His Sacred History of the World, from which the quotation is taken, I earnestly recommend to the attentive perusal of students of natural history.

completely out of the water, that they seem to merit the appellation of amphibious. Of these the Patéllæ and the Littorinæ (Turbo Lin.) are remarkable examples. Our common species of the latter genus (Túrbo littòreus and Nerìta littoràlis of British conchologists) seem indeed to prefer spots where they can be covered only at high water, and I have seen myriads of them, when young, clustered in hollows of rocks that were many feet above the highest tides. Still, their respiratory organs are, as they ever have been, branchial; nor does it seem easy, on the Lamarckian hypothesis, to account for their non-improvability: why these shell-fish, so fond of air, have not acquired, by their residence in it, the lungs of the snail, and betaken themselves to the land; why their shells have not become lighter, to enable them to move with more alacrity; and why their eyes have not risen to a higher elevation than the base of the tentacula, that they might scan the landscape, and avoid its perils. The habits of the Chitónidæ are similar to those of the Littorinæ. "Those animals," says the Rev. Mr. Guilding, "frequent the rocks and stones of the sea-coast, and are distributed nearly over the whole globe. Many of the species are constantly under water, while others ascend above low or even high water mark, spending the day exposed to the hottest sun, or selecting a resting-place which is only occasionally moistened by the rude and restless surf. In Chitonéllus and Cryptocónchus there are certain minute organs on the zone, which bear a strong resemblance to the spiracula of the annulose animals. From their habit of quitting the watery element, like many of the Turbínidæ, I once supposed that the organs for the aeration of the circulating fluid might be of a compound nature (pulmono-branchiàti). It is, however, far more probable (as in the case of some crustaceous genera which I am now investigating) that this process is capable of a diurnal or a temporary interruption, or that the branchiæ, so long as they are kept moist, and shielded from atmospheric influence, may perform their functions, though much more slowly." (Zool. Journ., vol. v. p. 29.) I shall continue this subject in my next.

April 23.

G. J.

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ART. XIV. On the Distinctions between the Linnæan Genera Potentilla and Tormentilla. By CHARLES C. BABINGTON, B.A. F.L.S. &c.

THE genera Potentilla and Tormentilla are allowed by Linné to differ only in number *, and it has long appeared to me that those botanists who consider them as forming parts of one and the same genus conform more exactly to the Linnæan rules (which are also those of nature) than he did himself. The genera must be admitted to be extremely close in habit, and the only other difference consists in the number of the petals and sepals, Potentilla having 10 sepals and 5 petals, and Tormentilla 8 sepals and 4 petals.‡ Number alone, therefore, being depended upon in this instance, the following tables, drawn up from the examination of 2794 specimens of Tormentilla officinàlis of Smith, cannot but be interesting. The specimens were gathered, at the latter end of last August, in Needwood Forest, Staffordshire.

The calyx in the genera now under consideration appears to consist of two whorls of sepals, alternating with each other, of which one (the outer?) has generally much smaller sepals than the other. I have, therefore, in the tables, distinguished them as "large" and "small." The large whorl, which is alternate with the petals, does not appear to vary much in

Linné says, under Potentilla, in his Genera Plantarum, ed. of 1767, "Deme unicam quintam partem numero in omnibus partibus fructificationis, et habebis Tormentillam." [Take away from the number of the parts of fructification in Potentilla a fifth part, and you will have the genus Tormentilla.] He also says, under Tormentilla, in the same work," Tormentilla solo numero differt a Potentilla, hinc possent ambo genera combinari." [The genus Tormentilla differs from Potentilla in number alone, and hence these two genera may be united.]

The rules to which I refer are the following, which he strongly im presses on all botanical students:-" Scias characterem non constituere genus, sed genus characterem ; characterem fluere e genere, non genus e charactere; characterem non esse, ut genus fiat, sed ut genus noscatur." (Lin. Philosophia Botanica, p. 119.) [You should know that a character does not constitute a genus, but a genus a character; that a character proceeds from a genus, not a genus from a character; a character is not formed that a genus may be constituted, but that a genus may be known.] I append the essential generic character, copied from Lin. Systema Naturæ, ed. 12. p. 350. and 352.: "Potentilla, cal. 10-fidus, pet. 5; sem, subrotunda, nuda, receptaculo parvo exsucco affixa." [Calyx 10-cleft, petals 5; seeds roundish, naked, affixed to a small dry receptacle.] "Tormentilla, cal. 8-fidus, pet. 4.; sem. subrotunda, nuda, receptaculo parvo exsucco affixa." [Calyx 8-cleft, petals 4; seeds roundish, naked, affixed to a small dry receptacle.] The characters given by Sir J. E. Smith and Dr. Withering, although not exactly in the same words, do not at all differ in sense. Dr. Withering says that he keeps them distinct, as "more favourable for investigation:" see his Botanical Arrangement, ed. 3. vol. ii. p. 476.

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size or shape; but in the smaller one I have noticed the sepals so large as to equal the others, and so small as to be hardly visible: their shape also is generally ovate-lanceolate, but I have seen them both linear and broadly ovate.

TABLE I.-Showing the condition and number of each of 15 distinct varieties found in the examination of 2794 specimens. The fractional parts refer to those cases in which one or more of the sepals is notched more or less deeply at the extremity: means that one sepal was notched; that the notch occurred in two of the sepals in the same flower; that it was so in three.

TABLE II.

Stating the number of times that the several variations in each whorl occurs in the whole number of specimens.

It appears to me that the result to be deduced from the above is, that those botanists are in the right who, with De Candolle, consider Tormentilla officinalis as a species of the genus Potentilla under the name of Potentilla Tormentilla.

CHARLES C. BABINGTON.

* In this variety one sepal was half converted into a petal.

+ This had one sepal lower than the others.

These varieties had two bracteas just below the flower.

An attentive inspection and comparison of plates 862, 863, and 864. of English Botany will much elucidate the above communication; in the absence of dried specimens, which are better, or living ones, which are better still, of the plants there depicted: they are these: -On plate 862. Potentilla réptans L., where the back view of a flower merits attention; on plate 863., Tormentilla officinalis Smith; and on plate 864, Tormentilla réptans L.

The question proposed is:- Are not the tormentils rather potentillas usually possessed of only four fifths of their sepals and petals? or, in other words, should the genus Tormentilla be preserved, or abolished and its species transferred to the genus Potentilla? Contributive to the answering of this question, Mr. Babington has provided the amplest list of instances of the condition of the flowers of Tormentilla officinalis Smith ever before published; and worthy of admiration is the zeal which led him to collect so many, and the skill with which he has arranged and adapted them in relevance of the question. Besides the value of these instances in this relation, they, and those of the floral variations of Paris quadrifòlia L., communicated by Professor Henslow (Vol. V. p. 429. 755.), have a universal and permanent value in their subservience to arguments on every analogous condition of other plants and genera. Farther than this, we think the facts themselves, extensively detailed though they be, very interesting; for who that loves plants can possibly be wearied with the minutest incident in the, as it were, personal biography of any one of them. Dilated premises too, enable the student to canvass and analyse the conclusions deduced, and, if dissatisfied with them, to draw others for himself. We neither presume nor profess to place ourselves in this latter relation to Mr. Babington's conclusion, but beg to attach some quotations and remarks which more or less oppose it, or otherwise relate to it. Smith, in his English Flora, vol. ii. p. 426., contends for the due distinctness of the genus Tormentilla from the genus Potentilla, and presents a clearly drawn view of, and most pertinent remarks on, their relations: these merit the attention of the reader. We select two remarks: - First, "The distinction between Tormentílla and Potentílla certainly depends upon number; but the difference is obvious, and as constant as in any other similar instance, of which there are several universally adopted." (p. 426.) Secondly, in the detailed descriptions of Tormentilla officinalis (in p. 427.):-"The flowers have, very rarely indeed, 5 petals, and consequently 10 segments [sepals], to the calyx; an accident not uncommon in several [species of]