374 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



nerically. It will be seen to present nearly the same surface-ornamentation 

 as our Pyropsis Bairdi ; but its more produced spire, and much shorter bent 

 canal, non-perforate axis, &c, seem to forbid its near association with that 

 type. Dr. Stoliczka lias described two Indian Cretaceous forms under the 

 names Lagena nodulosa and L. secans, that certainly present many strong 

 points of resemblance to a variety of the type of the section here under con- 

 sideration. I do not believe, however, that such shells can be properly ranged 

 under the name Lagena, Klein, even if that author could be cited as the 

 founder of genera, since his figured type of that genus differs widely in having 

 evenly-rounded volutions, without traces of revolving carinae, and a much 

 shorter, wider, and less bent canal ; while H. and A. Adams, who ought to 

 to be regarded as the real founders of the name Lagena, if it is to take a 

 place in conchological nomenclature, apply it to forms like Klein's type. 



The reason for doubting the generic, and even subgeneric, identity of 

 the Indian Cretaceous forms mentioned, with the type of the group here 

 placed as a section of the genus Fusus, under the name Serrifusus, is the 

 presence of what appears to be a broad, low varex, on one of Dr. Stoliczka's 

 figured specimens. 



From all that is now known in regard to the geological range of the 

 genus Fusus, it possibly may have been introduced during the Cretaceous 

 epoch. It became more extensively developed, however, in Tertiary times; 

 while it is well represented and widely distributed in our existing seas, par- 

 ticularly those of China, Australia, and the distant eastern countries. 



F ii s u s ? (Serrifusus) Dnkotcnsis M. & H. 



Plate 31, fig. 11 ; and pi. 3-2, figs. 6, a, b. 



Fusus DaJcotensis, Meek and Haydcn (1856), Proceed. Acad. Nat. Soi. Philad., VIII, (35. 



Fusus (Neptunea) Dakotensis, Meek and Haydeu (I860), ib., XII, 421. 



Tudirla' Dakotensis, Meek (18(>4), Smithsonian Check-List N. Am. Cvet. Fossils, 23. 



Shell rhombic-fusiform, attaining a rather large size; spire conical, less 

 than the length of the aperture and canal; volutions about five and a half to 

 six. convex, with upper side obliquely flattened, and a prominent nodose 

 carina passing around below the middle of those of the spire, and around the 

 middle of the last one, which latter is ventricose, and bears a second smaller 

 revolving ridge below the principal one, and a much smaller third one farther 

 down; nodes of the principal carina compressed above and below; beak 

 rather short, and bent backward below; columella moderately arcuate and 



