12(3 pal.t:ontolo(;y. 



at first, and the general form always remains similar. The septa are, how- 

 ever, very distinct; the lobes and cells, so far as they could be traced, hav- 

 ing much more simple outlines. The pilse do not extend across the abdomen 

 at first, but leave a smooth band in the center. This is broken up on what 

 is supposed to be the fifth volution by tlie extension of the pilfe across the 

 abdomen." — (A. II.) 



Localitjj and position. — New Pass, Desatoya Mountains, Nevada; Trias. 



The following two types Professor Hyatt views as representing two 

 undesoribed genera, in regard to the family relations of which lie has 

 expressed no opinion. His attention was called to them after he had sent 

 on his paper on the others ; and in returning the specimens, he also sent the 

 notes quoted below respecting them. These notes he seemed rather to 

 regard as suggestions than as full descriptions, as he stated that I might as 

 well go on and name and describe them myself It seemed more proper, 

 however, as he had investigated the whole, that these also should stand in 

 his name. Consequently, I have selected the names, and take the liberty 

 to insert them here on his authority, quoting his notes in regard to them. 



Genus EUTOMOCERAS, Hyatt. 



fi'(.augm. part.) ; ro/zi^r, wharp ; /.f'/mf, a lioru. 



" This is a well-marked type, characterized by its lenticular form, nar- 

 row umbilicus, apparently at all ages very sharp abdominal keel, without 

 furrows or lateral ridges, and small regular arched pilaj on middle-sized 

 specimens, growing wider, more irregular, less distinct, and developing 

 small lateral nodes on the adult, with both nodes and pilse becoming obso- 

 lete on the larger part of the body-volution." — (A. H.) 



EuTOMOCERAS Laubei, Meek. 



Plate 10, figs. 8 aud 8 a. 



Shell compressed-lenticular, with the periphery very acutely carinated; 

 umbilicus small, or scarcely more than one-sixth the greatest diameter of 

 the shell. Volutions much compressed laterally, with tlie sides gradually 



