104 
GEOLOGICAL REPORT—THIRTY-FIFTH PARALLEL. 
PRODUCTUS ROGERSL—Plate II, figs. 14, 15. 
Productus Rogersi, Noriuood and Pratten , in Journal Acad. Nat. Scien., Philadelphia, Vol. 
Ill, 1854, page 9, plate I, fig. 3. 
“ Shell of medium size, slightly transverse ; dorsal valve very high and strongly enrolled on 
itself; cardinal border equal to about four-fifths of its greatest transverse diameter; beak rather 
large, and passing beyond the cardinal border ; ears but little distinct from the dorsal vault. 
The anterior part is flattened, and possesses a slight sinus. The surface is covered with ribs, 
of which twelve may be counted in the space of ten millimetres, at the distance of ten milli¬ 
metres from the beak. It is also covered in its whole extent with transverse folds. Those 
nearest the beak are rather small, but after passing the visceral disc they rapidly increase in 
size to near the middle of the shell, after which they again decrease in size to the margin. 
The whole anterior portion of the shell seems to have been pretty thickly covered with tubercles, 
especially between the transverse bands, while a few were distributed over the remainder of the 
surface.” 
The dorsal valve is inflated and extremely arcuate ; .the beak incurved and extending slightly 
beyond the cardinal line ; mesial line flat or subdepressed ; surface (in a partially exfoliated 
condition) marked by interrupted longitudinal ribs and stronger concentric undulations or 
ridges, which are stronger towards the beak. Where not exfoliated, the longitudinal ribs are 
interrupted only by the concentric undulations, which, at the crossing, sometimes produce a 
slight nodulosity. In the exfoliated shell, the longitudinal ribs are often not continuous across 
the concentric undulations ; and they appear as if gradually rising from the surface, and termi¬ 
nating suddenly below, as if forming the base of a spine. In the same specimens there is 
frequently a row of deep pits between the concentric undulations, with numerous finer punctas. 
A single specimen shows the prominent round bases of a few spines upon the front and central 
parts of the shell. The ventral valve is strongly marked upon its upper part by nearly equal 
longitudinal and concentric ridges, the latter becoming fainter below the curvature of the shell; 
surface of the ventral valve nodulose at the crossing of the two sets of lidges. 
The figures of Messrs Norwood and Pratten are not unlike some European figures of P. 
p)ustidosus , but these gentlemen compare the shell with P. undatus as its nearest analogue. 
Our specimens are unlike DeKoninck’s figures of the latter, and more resemble those of the 
former species. 
We have in our collection authentic specimens of this species from Springfield, Illinois, which 
are clearly identical with the specimens under examination. 
Locality. —Pecos villages, in the coal measures, or upper carboniferous limestone. 
Imperfect specimens , the specific characters of ivliich are obscure or indeterminable. 
No. 123.—“ Polypier du lower carboniferous, Rocky mountains.” These specimens contain 
remains of Zaphrentis and Cyathojjhyllum, of carboniferous types. 
No. 123-^.—“Polypier briozoaire, of the coal measures near to Choctaw agency.” This 
specimen contains remains of Fenestella. It appears to be a portion of a transported mass, one 
of the surfaces be ng worn smooth. 
No. 124. “Delaware Mount, Camp 19.” Several specimens from this locality contain a 
species of orthis, but too imperfect to be identified. It is evidently a carboniferous form. A 
specimen from the same place, No. 59 of catalogue, is a compact, crystalline, buff-colored lime¬ 
stone, containing crinoidal fragments. 
No. 125.—“Fossils of the lower carboniferous, Shawneetown.” Some specimens marked 
“ Shawneetown” are a fine-grained sandstone, with numerous casts and fragments of crinoids, 
a species of Productus, a Nucula, and a i impression of Pleurotomaria sphcerulata. 
No. 127.—“ Encampment creek, Jurassic inferior.” A specimen with this label and marked 
