ORDOVICIAN FAUNAS. 127 
MOLLUSCA. 
GASTROPODA. 
CYRTOLITES sINUATUS H. & W. 
Plate IV., Fig. 9. 
18%". Cyrtolites sinuatus H. & W., U. S. Geol. Expl., 40th par., vol. 
Ue) arse ty elles Tp uileae i ros 
Description.—Shell laterally compressed, composed of about twoi( ?) 
slightly-embracing volutions. Cross-section of the outer volution sub- 
triangular, the dorso-ventral diameter much greater than the lateral. 
Sides of the outer volution marked by a broad depression, which 
produces a conspicuous carination upon the dorsum of the shell for 
one-half the entire width of the outer volution.. At the inner border 
of this depression the sides of the shell are somewhat abruptly ele- 
vated, then are rather narrowly rounded, dropping almost vertically 
into the umbilicus. The umbilicus large, exposing the inner volutions. 
The maximum diameter of the only specimen observed is 8 mm. 
Remarks.—The single specimen of this shell which has been ob- 
served in the New Jersey collections has only one side exposed. It 
agrees with the description and illustrations of the typical C. sinuatus 
described from the Pogonip limestone of Nevada, except that the 
lateral compression of the outer volution is even greater than in the 
Nevada shell, so that the portion of the shell immediately surround- 
ing the umbilicus stands up conspicuously as a rounded ridge. 
BELLEROPHON? sp. undet. 
A single, imperfect specimen of a minute species of a Bellerophon- 
like shell has been observed in this fauna near Columbia. The 
diameter of the specimen is less than 5 mm. 
