39 Ithaca Group 39 



species. They are much smaller than the specimen figured by 

 Hall, and have the dorsum flat instead of rounded as in that 

 species. 



Bellerophon ithacensis n. sp., PI. i, figs, i, 2. 



The specimens on which this species is based are somewhat 

 distorted and crushed. 



Shell of medium size. Width of flattened specimen greater 

 than the length. The aperture is considerably expanded. Vo- 

 lutions apparently not more than one or two. The dorsum is 

 marked with a sharp elevated carina. 



The surface is marked by a peculiar wrinkling, varying in its 

 development from roughly transverse striae to a pustulose or 

 reticulate surface. 



The ornamentation of this species is unique, readily distin- 

 guishing it from any other of the genus. 



From the Ithaca group, station 1-13. 



Macrocheihis {Holopea) macrostomusf Hall. 



A single well-preserved specimen of this genus has been ob- 

 tained from station 6-1, in the lower part of the Ithaca group. 



Platystoma lineatum var. callosum Hall. 



This gastropod is rather common in the University quarry as- 

 sociated with Spirifer mesacostalis and ^. mesrstrialis. 



Platyceras carinatu'>n Hall. 



Common at a few localities in the Ithaca group. 



Cephalopoda. 



Orthoceras fulgiduni Hall. 

 This is rather rare in the Ithaca group. 



Orthoceras leander Hall? 



A few specimens from the Ithaca group are referred to this 

 species. 



Orthoceras pecator Hall. 



Two specimens were obtained from the Ithaca group at sta- 

 tion 2-12. 



Orthoceras ayiguis Hall. 



Occurs in the upper Spirifer Icevis zone of the Portage. 



