270 POTTSVILLE FAUNA OP OHIO 



intervening from crest to crest on the last volution. Sutures about 

 7 mm. apart near the living chamber but gradually becoming closer 

 together, about 5 mm. intervening at the beginning of the second 

 whorl; ventral lobe deep but regularly convex; lateral lobe rather nar- 

 row, not so deeply convex as ventral lobe; lobe on impressed zone- 

 deeply convex and angular along the median line; dorsal lobe flattened 

 and scarcely perceptible; saddles abruptly curved on ventrilateral 

 angles, less so on umbilical shoulders and almost imperceptible on the 

 angles on either side of the impressed zone. Siphuncle centridorsal. 

 Shell thin and where preserved marked by extremely fine revolving lines. 



Dimensions. Greatest diameter of shell exclusive of living chamber 

 which is incomplete, 72 mm. 



Remarks. This species of Metacoceras seems most closely related 

 to M. cornutum and M. dubium. From the former it differs principally 

 in having the whorls narrower in comparison to the height, the impressed 

 zone narrower and more angular, and the nodes farther apart and 

 situated opposite each other on either side of the ventrum, while in 

 M. cornutum they occupy alternate positions. From M . dubium it can 

 be distinguished by the narrower outline of the whorls, and by the 

 form of the venter, which in M. dubium is marked by longitudinal swell- 

 ings on either side of a depressed central zone . The Ohio form is repre- 

 sented in the collections studied by a single specimen from the Lower 

 Mercer limestone. 



Horizon and locality. Lower Mercer member: Lawrence County, 

 near Hanging Rock, Locality 30, r. 



Metacoceras sp. 



Description. The fragments of the outer whorl of two individuals 

 probably belonging to the genus Metacoceras and apparently represent- 

 ing two distinct species are present in the Me Arthur limestone. The 

 nodes on the ventrilateral shoulders are highly elevated and are more 

 closely arranged on one specimen than on the other. The material at 

 hand, however, is too crushed and imperfect to render specific determi- 

 nation possible. 



Horizon and locality. McArthur limestone: Hocking County, 

 mine of Logan Clay Products Co., Locality 86, r. 



Genus Endolobus Meek and Worthen 

 Endolobus (Temnocheilus ?) ortoni (Whitfield) 



1882 Nautilus ortoni. Whitfield, Ann. N, Y. Acad. Sci., Vol. 2, p. 231. 



Coal Measures: Springfield, Summit County, Ohio. 

 1891 Nautilus ortoni. Whitfield, Ann. N. Y. Acad. Sci., Vol. 5, p. 601, PI. 16, Fig. 20. 



Coal Measures: Springfield, Summit County, Ohio. 



