Strophomena and Other Fossils 
57 
In a similar manner, the flatter, more quadrate forms occur in 
central Kentucky, chiefly in the upper part of the Fairmount, 
especially where the number of specimens is small, and the species 
evidently is disappearing 
Regarding Strophomena maysvillensis as only the more vigorous 
form of Strophomena planoconvexa, the distribution of the former 
should be added to that of the latter, in order to secure a com- 
plete account of the geographical and vertical distribution of 
Strophomena planoconvexa. 
Strophomena sinuata, Meek® 
{Plate I, Figs. 3 A, B, C) 
Strophomena sinuata was described by Meek, probably from 
material supplied by U. P James. In the James collection, in the 
Walker Museum at Chicago University, there are several entire 
specimens, numbered 56, and labelled as types of Strophomena 
sinuata, among which none of the specimens figured by Meek 
{Ohio Paleontology , vol. i, plate 5, Figs. 5, a-d) could be identi- 
fied. They probably are a part of the series from which Meek 
secured his material. Similar statements may be made of most 
of the other Cincinnatian specimens figured by Meek, unless the 
specimens were very rare and were returned to some private col- 
lection. 
Compared with Strophomena sulcata, the shells of Strophomena 
sinuata are somewhat larger, frequently equalling 25 mm. and 
sometimes attaining 30 mm. in width The general outline is 
about the same, and usually there is no great difference in the 
amount of sinuosity of the valves anteriorly, although compara- 
tively deep and narrow sinuses are not uncommon in Strophomena 
sulcata, and are comparatively rare in Strophomena sinuata. 
The chief diflhrence consists in the coarseness of the radiating 
striae. Of these there are about 6 to 7 within a width of 5 mm. 
near the anterior margin, or 36 to 40 within 1 cm. of the beak, 
occasionally equalling 42 or even 45. Usually the brachial valve 
appears more convex from front to rear; this is due partly to 
the fact that the median elevation curves downward below the 
general plane of the flattened area which is located anterior to 
® Ohio Paleontology, vol. i, p. 87, 1873. 
