TRKMATODISri S. (JIMOMIA, ETC. 217 



Subgenus Temnocheilus, McCoy. 



Shell carinated, with an open, conical umbilicus. 

 Five species. Garb, limestone. 

 T. BIANGULATUS, Sowb. PI. 98, fig. 503. 



Subgenus Trematodiscus, Meek and Worthen. 



Like TemnocheiluK, but dorsal or outer side of whorls with 

 revolving angles and sulci, and frequently, revolving stri;v 



Carboniferous. Europe; America. 



T. TRisuLCATrs, Meek and Worthen. PI. 98. fig. 504 0, b. Sub- 

 carboniferous. Rockford. Ind. 



Subgtmis Cimomia, Conrad. 



Septa sinuous, double waved or sigmoid, numerous ; siphon 

 small, central. 

 N. BURTONI, Galeotti. Lower Eocene. 



Snbgcnus Hercoglossa, Conrad. 



Septa angular and linguiform ; apex of the angle or tongue- 

 shaped lobe not contiguous with the adjacent septum ; siphon 

 large or moderate, situated within the centre, or between the 

 middle and the inner margin, and not dorsal or funnel-shaped, 

 but tubular and gradually tapering. 



Eocene. Cret. Europe ; America. 



A very doubtful group, as Conrad includes species having 

 respectively the characters of Aturia and of Nuiitihix ; the 

 type species, however, N. orbiculatus of Tuomey, has not been 



figured. 



Submenus Pseudonautilus, Meek. 



Differs from Hercoglossa in the septa being provided with a 

 well-defined peripheral and antiperipheral lobe, and the siphuncle 

 placed near the outer margin. 



NAUTILUS GEINITZI, Oppel. 



Submenus Cryptoceras, d'Orb. 



Planorbiform ; septa arcuated, without lobes or sinuosities; 

 siphon dorsal. 



Two species. Devonian, Carboniferous. Europe. 



C. SUBTUBEECULATUS, d'Orb. PI. 98, fig. 504. 



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