Apr. 1899. Palkontology of Upper Cretaceous Series — Logan. 211 



is oval in form with a smooth periphery; it is turned inward toward 

 the coil of the shell. 



" Septa are provided with moderately broad lobes and sinuses. 

 The siphonal lobe is longer than wide, and bears two rather promi- 

 nent lateral branches, each of which is unequally bifid, and digitate. 

 The first lateral sinus is about the size of the siphonal lobe and has 

 approximately the same width at the base; it is divided at its 

 extremity into two unequal lobes both of which are bifid, the one 

 nearest the siphonal lobe having its lobes again subdivided; first lat- 

 eral lobe, about the size of the siphonal lobe, divided at its extremity 

 into two tripartite lobes each of which is digitate; second lateral sinus 

 shallow, divided into two rounded lobes each of which is slightly 

 indented; second lateral lobe tripartite, central division not divided, 

 other two bifid; third lateral sinus small bifid; remaining portion of 

 septa not visible." 



Suturally our type is very closely allied to S. ventricosus Meek, 

 and it is quite probable if they do not belong to the same species 

 that they are varieties of the same species. The specimen here 

 described is much larger than Meek's type of S. warreni, but it has 

 the same general form. It resembles the former species in aperture 

 and suture, and the latter in body shape and costae. It is the belief 

 of the writer that .9. warreni, S. wyomingensis and S. ventricosus are 

 varieties of the same species. 



PRIONOTROPIS WOOLGARI— Meek. 



U. S. Geol. Survey of the Territories, Vol. IX, p. 455. 1867. 

 (PI. XXIV, Figs. 1 to 6. Mus. No. P 5931.) 



Further collecting and study of this form may reveal a new 

 species. A comparison of the suture of P. woolgari with the suture 

 of the form here figured and placed provisionally in the above species 

 reveals many differences. However, these differences may be only 

 such as exist between the young and the adult individuals of the same 

 species. As the sutural differences seem to be the only well marked 

 ones the original description will be given here and the reader asked 

 to make the comparison of the figures. 



"Shell attaining a medium size, more or less compressed dis- 

 coidal, the outer turn being proportionally more convex (including 

 nodes) than those within; each volution embracing about one-fifth of 

 the next within, and having its umbilical margin slightly indented by 



