WHITE] CARBONIFEROUS FOSSILS. 121 
irregularly polygonal, averaging about five millimeters in diameter, their 
outer surfaces faintly marked by vertical lines indicating the places of 
the septa, but they are not sufficiently distinct to give acrenulated bor- 
der to the calyx; the outer surfaces also present more or less distinct 
irregular transverse wrinkles or undulations; outer wall of the corallites 
distinct, but not thick ; inner wall well developed, diameter of the space 
inclosed by the inner wall equal to about one-half the full diameter of 
the corallite; transverse tabule of this central space well developed, dis- 
tinctly separate from each other, their number being about ten to each cen- 
timeter of length of the corallite. The space between the outer and inner 
walls is occupied by numerous, more or less complete, shallow, infundi- 
buliform plates, not quite so numerous as the central tabule, which, 
springing from the inner wall, and which wall they successively heip to 
form, arch upward and outward to the outer wall. These infundibuli- 
form plates are the successively abandoned floors of the outer portion 
of the calyces. They appear to have been usually, but not always com- 
plete, either as regards their extension to the outer wall or their con- 
struction of a symmetrical cup, but they are generally approximately 
perfect in these respects. 
The condition of the only specimens discovered is not such as to show 
any of the calyces in their natural condition, and the structure of the 
corallites has therefore been determined by polished sections, both lon- 
gitudinal and transverse. While the parts already described are thus 
distinctly shown, the rays are discovered with difficulty, and they 
were evidently only slightly developed. Their number appears to have 
been sixteen or seventeen. 
Acervularia has been regarded as characteristic of Devonian strata ; 
but as related genera are common to both Devonian and Carboniferous 
strata, there seems to be no reason why Acervulariamay notbeso. This 
species, however, differs somewhat from the typical examples of the 
genus, but the difference is apparently no greater than we should ex- 
pect it to be in the case of related forms occurring in strata of so much 
later date than those which contain the typical forms. 
Position and locality—Carboniferous strata, Blackfoot range, south of 
the Yellowstone National Park, where it was discovered and collected 
by Prof. O. St. John. 
Genus LEPTOPORA Winchell. 
LEPTOPORA WINCHELLI White. 
Plate 34, fig. 11 a. 
Leptopora winchelli White, 1879, Bull. U. 8. Geol. Sur. Terr., vol. v, p. 211. 
Among some collections which were brought in by Dr. A. C. Peale, in 
the autumn of 1877, from near the forks of Logan River, in Bear 
River range, near the northern boundary of Utah, are a few specimens 
of Leptopora. This genus of corals was proposed by Prof. Winchell in 
Proce. Acad. Nat. Sci. Philad., 1863, p. 2, for a peculiar form, the first, 
and hitherto the only, known species of which occurs in the Kinderhook 
division of the Subcarboniferous Group, at Burlington, Lowa. This 
form is so rare and consequently so little known, that I quote here Prof. 
Winchell’s generic diagnosis as a necessary aid in the description of 
the species. 
“Oorallum occurring in thin discoidal masses; cells very shallow, 
crowded, polygonal, separated by a common cell-wall, which is vertically 
