NATURAL SCIENCES OF PHILADELPHIA. 87 



diameter at the same place, 1.27 inches. The increase in size is 

 such that the same measurements at a point three inches farther 

 forward, are respectively 1.56 and 1.50 inches, while from this 

 point to the broken anterior end, which includes only about one 

 inch of the body chamber, the shell diminishes a little in both 

 diameters, but apparently more in the transverse than the dorso- 

 ventral, though this may be in part due to accidental lateral 

 pressure. 



This species seems to be related to Crxjptoceras eitgemum, Hall 

 (Regents' 15th Report, p. 70, pi. 9, figs. 1, 2, and 3), but evidently 

 not only attained a larger size, but differs in having its dorso- 

 ventral diameter a little greater than the transverse, instead of the 

 reverse. It also differs in being marked with distinct longitudinal 

 raised lines, as well as in tapering somewhat, from the central re- 

 gion forward, and in having its septa more closely arranged. In 

 form it agrees more or less nearly with several of the Bohemian 

 species figured by Dr. Barrande, but it differs from all of them in 

 its surface markings ; while from his C. pugio^ which has some- 

 what similar sculpturing, it differs in being a little more curved, 

 and without transverse undulations. 



The entire shell could scarcely have been less than 12 to 14 

 inches in length, and probably curved so as to form about one- 

 fourth of a circle. 



Locality and position. Dublin, Franklin Co., Ohio. Cornife- 

 rous group of the Devonian series. 



GYROCEKAS (TKOCHOCERAS ?) OHIOENSE, Meek. 



Shell attaining a large size, oval-subdiscoid ; composed of thi-ee 

 or four rather rapidly enlarging whorls, the inner ones of which 

 are closely contiguous, while the last one seems to become a little 

 free at the aperture; umbilicus large and of moderate depth. 

 Volutions rounded — subquadrangular, with the transverse dia- 

 meter somewhat greater than the dorso-ventral ; rather broadly 

 flattened on the periphery, and compressed convex on the sides, 

 which round off gradually into the umbilicus, and more abruptly 

 to the periphery, excepting in young shells, which have the sides 

 of the volutions more flattened, and rounding as abruptly into 

 the umbilicus as to the flattened outer side. Septa moderately 

 distant, or separated by spaces which measure, on the middle of 

 each side, about one-third the dorso-ventral diameter of the volu- 

 1871.] 



