Family ENTALOPHORIDÆ Reuss.

Zoarium ramose, branches free, subcylindrical, with rounded and more or less prominently exserted zoocial apertures opening on all sides of the branches.

MITOCLEMA Ulrich.

Zoarium ramose, cylindrical, consisting of long tubular zoœcia, which are thin-walled and prismatic in the axial region, diverge gradually from the center, and bend abruptly outward near the surface, often becoming free and much exserted; apertures terminal, circular, usually arranged in regular transverse or subspiral series.

Genotype: Mitoclema cinctosum Ulrich. Ordovician. Two described and one new species.

CLONOPORA Hall.

Zoarium ramose; branches cylindrical, consisting of elongate tubular zoœcia, cohering for part of their length, then bending outward and becoming free; apertures terminal, not contracted, arranged in rings or spirally around the branch.

Genotype: Clonopora semireducta Hall. Devonian. Three species.

DIPLOCLEMA Ulrich.

Zoarium dendroid, branches slightly compressed, spreading in the same plane; zoœcia tubular, diverging from a wavy mesial mesotheca; apertures circular; prominent.

Genotype: Diploclema trentonense Ulrich. Ordovician, Silurian. Two species.

CYSTOPORA Hall.

Zoarium cylindrical, consisting of tubular, ampullate zoœcia, cohering for the greater part of their length; distally the zoœcia bend outward, becoming free and much contracted; apertures terminal.

Genotype and only known species: Cystopora geniculata Hall. Devonian.

Family PHACELOPORIDÆ Ulrich.

PHACELOPORA Ulrich.

Zoarium articulated; zoccia conical, two or more aggregated to form cone-shaped bundles; apertures subterminal, circular, and slightly contracted.

Genotype and only described valid species: Phacelopora pertenuis Ulrich. Ordovician. One new species in the Clinton group.

Family CERAMOPORIDÆ Ulrich.

Zoarium variable; maculæ or clusters of mesopores or of zoœcia larger than usual at regular intervals; zoccia tubular, at first prostrate, continue obliquely or directly to the surface, often with a few diaphragms; apertures commonly oblique, provided with a lunarium; mesopores generally present, always irregular and usually without diaphragms; walls minutely porous, formed of intimately connected and irregularly laminated tissue.

CERAMOPORA Hall.

Zoarium discoidal, free or attached by the center of the base; under surface with one or more layers of small, irregular cells; zoœcia radiating out on the upper surface from a depressed center; apertures oblique, imbricating; mesopores short, irregular, decreasing in number from center to margin.

Genotype: Ceramopora imbricata Hall. Silurian.

CERAMOPORELLA Ulrich.

Zoarium of incrusting layers, which by superposition may form masses; zoœcia short, tubular with thin walls; apertures oval, oblique, the lunarium forming a hood; mesopores abundant, often completely encircling the zoœcia.

Genotype: Ceramoporella distincta Ulrich. described and twenty new species.

CREPIPORA Ulrich.

Ordovician. Nine

Zoarium incrusting, lamellate or massive, or, in one species, forming hollow branches; zoœcia long, tubular, thin-walled, with diaphragms; apertures angular or subpyriform, lunarium not overarching, its ends usually projecting; mesopores generally restricted to the maculæ, which are elevated or depressed.

Genotype: Crepipora simulans Ulrich. Ordovician. Eight described and six new species.

CHILOPORELLA Ulrich.

Zoarium forming parasitic sheets, from which rise flabellate fronds or compressed branches; zoœcial tubes long, thin-walled, irregular in shape in immature region, near the surface walls much thickened, diaphragms rarely developed; apertures ovate, lunarium conspicuously elevated; mesopores numerous.

Genotype and only described species: Fistulipora? flabellata Ulrich= Ceramopora nicholsoni James. Ordovician.

COELOCLEMA Ulrich.

Zoarium forming hollow branches, lined internally with a striated epitheca; zoœcia as in Ceramoporella, but with thicker walls.

Genotype: Diamesopora vaupeli Ulrich Ceramopora alternata James. Ordovician. Four described and three new species.

ANOLOTICHIA Ulrich.

Zoarium ramose, digitate, laminate, or incrusting; zoœcial tubes long, subpolygonal, intersected by remote diaphragms; lunarium elevated at the surface, traversed by two to six minute, vertical, closely tabulated tubes; mesopores sparingly developed.

Genotype: Anolotichia ponderosa Ulrich. Ordovician. Two described and three new species.

CERAMOPHYLLA Ulrich.

Zoarium erect, bifoliate, the two layers grown together back to back; in other respects like Ceramoporella and Cœloclema.

Genotype and only known species: Ceramophylla frondosa Ulrich. Ordovician.

BYTHOTRYPA Ulrich.

Zoarium massive or lamellate; zoocial tubes long, intersected by thin diaphragms; apertures subovate, nearly direct, lunarium large, well-raised; mesopores numerous, open at the surface, forming internally a very loose vesicular tissue.

Genotype: Fistulipora ? laxata Ulrich. Ordovician. Two species.

SCENELLOPORA Ulrich.

Zoarium simple, pedunculate, under surface epithecated; upper surface slightly concave and celluliferous; zoœcial apertures occupy the summits of low ridges radiating from the center.

Genotype and only known species: Scenellopora radiata Ulrich. Ordovician.

SPATIOPORA Ulrich.

Zoarium forming thin crusts, usually on Orthoceras; zoccia very short, nearly direct; apertures irregular, with blunt spines at the angles, no lunarium developed; elevated, elongated maculæ usually a conspicuous feature.

Genotype: Spatiopora aspera Ulrich. Ordovician. Ten described and seven new species.

Family FISTULIPORIDÆ Ulrich.

Zoarium massive, lamellate or ramose, showing on the surface at irregular intervals maculæ or monticules composed of clusters of vesi

cles and of zoœcia slightly larger than the average; lunarium generally well developed, sometimes wanting; zoœcial tubes cylindrical or somewhat compressed, thin-walled, with diaphragms; walls minutely porous; apertures usually direct, closed at times by perforated covers; vesicular tissue occupies the interzoœcial space.

FISTULIPORA McCoy (LICHENALIA Hall, in part, DIDYMOPORA Ulrich, DYBOWSKIA and DYBOWSKIELLA Waagen and Wentzel, FISTULIPORELLA Simpson).

Zoarium massive, lamellate, ramose, parasitic or free; under surface with a wrinkled epitheca; zoccia cylindrical or somewhat compressed, direct or almost so, thin-walled until near the surface, and provided usually with a few diaphragms, and encircled by one or more series of vesicles; apertures subradially arranged about the maculæ, ovoid, subtriangular or pyriform, the lunarium more or less strongly developed; surface between apertures smooth or granular.

Genotype: Fistulipora minor McCoy = Calamopora incrustans Phillips. Range, Silurian-Carboniferous. Sixty-two described and a considerable number of new species.

CYCLOTRYPA Ulrich.

Like Fistulipora, but the lunarium obsolete and the zoœcial tubes circular in cross section.

Genotype: Fistulipora communis Ulrich. Devonian. Two species. Future work may disclose new species and show that species now referred elsewhere belong here.

ERIDOPORA Ulrich (PILEOTRYPA Hall).

Zoarium a thin, parasitic sheet; apertures oblique, subtriangular or ovoid; lunarium very prominent, overarching.

Genotype: Eridopora macrostoma Ulrich. Devonian, Mississippian. Four species described and several awaiting description.

HEXAGONELLA Waagen and Wentzel.

Zoarium as in Fistulipora, but the surface is marked off into generally hexagonal spaces, which are divided from each other by more or less elevated ridges, and usually have a macula in the center of the inclosed space.

Genotype: Hexagonella ramosa Waagen and Wentzel. From the Carboniferous of India. Two undescribed species from the Hamilton and Warsaw.

PINACOTRYPA Ulrich (FISTULIPORINA Simpson, FISTULICELLA Simpson).

Zoarium usually a thin contorted expansion, with a wrinkled epitheca on the basal surface; zoœcia thin-walled, with a few diaphragms;

interspaces wide, occupied by a single series of large angular mesopores with numerous diaphragms and never presenting the appearance of vesicular tissue; apertures subcircular, with a well-developed granose peristome, but no lunarium.

Genotype: Fistulipora elegans Rominger. Devonian.

CHILOTRYPA Ulrich.

Zoarium small, ramose, with a narrow, irregularly contracting and expanding axial tube; diaphragms few or absent; apertures elliptical, oblique, the lower margin thickened and elevated; interstitial vesicles commonly filled by a dense calcareous deposit near the surface.

Genotype: Chilotrypa hispida Ulrich. Range, Silurian-Mississippian. Eight described and five new species.

STROTOPORA Ulrich.

Zoarium ramose, with irregular branches. Like Fistulipora, but the surface presents distributed among the apertures large, abruptly spreading cells (regarded as broken ovicells); when perfectly preserved these appear as strongly convex elevations with a small opening on one side.

Genotype: Strotopora foveolata Ulrich. Devonian, Mississippian. Three species.

MEEKOPORA Ulrich.

Zoarium bifoliate, sometimes branching; the mesotheca thin and flexuous; zoœcia tubular, proceeding in a gentle curve from the mesotheca and opening somewhat obliquely upon the surface and provided with numerous, often recurved, diaphragms; apertures oblique, all pointing distally; lunarium, when present, not very prominent; rather large ovicells developed, showing at the surface as a convex space with a small apical opening.

Genotype: Meekopora eximia Ulrich. Range, Silurian-Carboniferous. Six described and three new species.

LICHENOTRYPA Ulrich.

Zoarium thin, incrusting; in its first stages like Fistulipora; as it matures, large spines and thin walls are thrown up about the apertures; numerous subangular vesicular openings interspersed among the apertures and scarcely distinguishable from them.

Genotype and only known species: Lichenotrypa cavernosa Ulrich= Lichenalia longispina Hall. Devonian.

BUSKOPORA Ulrich (ODONTOTRYPA Hall).

Like Fistulipora, but lunarium remarkably developed, projecting as a strong, bidenticulate process nearly half way across the aperture. Genotype: Buskopora dentata Ulrich. Devonian. Four species.