414 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



small, and sometimes simple ; si phonal lobe generally nearly or quite as large 

 as the first lateral; surface merely costate, or also variously nodose ; peri- 

 phery rounded, or, in nodose species, often somewhat flattened, and margined 

 on each side (especially of the last turn) by a row of larger nodes, rarely with 

 a central row between. 



As defined in the foregoing diagnosis, the genus includes several more 

 or less marked sections, some of which might perhaps without impropriety 

 be separated generically from the typical subdivision. These sections may 

 be separately defined as follows : 



1. macroscaphites,* Meek. 



Shell with inner turns merely in contact, or so slightly embracing 

 as to leave a very large, shallow umbilicus ; periphery rounded ; body- 

 portion much extended from the inner volutions ; surface costate. — 

 (S. gigas, Sowerby, and S. Ivanii, Puzos.) 



2. scaphites, Parkinson (typical). 



a. Shell with inner turns so deeply embracing as to leave only a 

 very small umbilicus, and often forming but a small part of the entire 

 bulk; volutions all rounded on the periphery; surface costate, but 

 without nodes, excepting sometimes a single row around the middle 

 of each side of the body-portion, which is always shorter than in the 

 last. — (Type as already stated.) 



b. Differs chiefly in form, by having the involute part generally 

 proportionally larger, and the deflected part shorter; also in having 

 periphery of body-part more or less flattened, with a row of nodes 

 along each of its margins, and sometimes another near the umbilicus. — 

 (<S. nodosus, Owen.) 



\c. Differs from the last in having three rows of nodes around 

 the periphery, which is rounded. — (<S. trinodosus and S. trulens, 

 Kner.) 



•I Lave here departed from the rule more generally followed, of commencing the series with the 

 typical section. Th s arrangement, however, is necessary in this case, in order to bring nearest together 

 the most nearly related sections. 



tThis should probably form a distinct subgenus; but I am unacquainted with the septa of these 

 shells. 



