16 PALAEONTOLOGY OF CALIFORNIA. 



aspect of some depressed subtrochiform species of Pleurotomaria, that it was not 

 until fully satisfied that the lines of growth, in crossing the flattened space between 

 the carina? on the outer side of the whorls, as well as in passing over the carinas, 

 make not the slightest backward curve, that I could be convinced there might 

 not have been a sinus in the lip, as in that genus. It differs from the type of 

 Sowerby's genus Euomphalus (E. pentangulatus), as well as from the other typical 

 species of that group with a more prominent spire, in having its whorls flattened 

 or broadly concave around the outer side, and flattened with an outward slope 

 above. It is also a much more ponderous shell, with a more oblique outline to 

 its lip, in consequence of which it projects much farther forward on the upper 

 than the lower side of the aperture. It also seems to have differed in having its 

 pcritreme scarcely continuous, or, at any rate, very thin on the side connecting 

 with the preceding whorl. 



I have some doubts in regard to the propriety of placing such shells in the same 

 genus with Euomphahcs pentangulatus ; but do so from deference to the opinions of 

 various authors, who insist upon making Sowerby's genus include a wide diversity 

 of forms. It may be regarded as the type of a group for which I propose the 

 name Omphalotrochus, including 0. antiquus= Solarium antiquum, d'Orbigny, from 

 the carboniferous rocks of Bolivia. (Voyage dans l'Amerique M&rid., p. 42, pi. 3, 

 figs. 1, 3.) 



The identity of Montfort's genus Straparollus with Euomphalus, Sowerby, would 

 seem to be very questionable, if any reliance can be placed upon Montfort's figure 

 and description of the type of his genus [Straparollus Dionysii). If they are con- 

 generic, however, Montfort's name will have to take precedence, as it has priority 

 of date ; and the group to which our shell belongs would then stand as a subgenus 

 under it, with the name of the type written Straparollus [Omphalotrochus) Whit- 

 neyi. 



The specific name of this fine shell is given in honor of Prof. J. D. "Whitney, 

 State Geologist of California. 



