Maryland Geological Survey 457 



typically imperforate ; inner lip smooth, and closely attached to the colu- 

 mella and body volution ; surface with vertical, sometimes node-like folds 

 around the most convex part of the volutions, and revolving stride, or small 

 ridges. 



" The foregoing diagnosis is drawn up so as to include, along with 

 Mr. Conrad's typical form, a group of apparently congeneric Upper 

 Missouri Cretaceous species, that still seem to differ in some of their char- 

 acters." — Meek, 1876. 1 



The genus is not known to occur except in the Upper Cretaceous. 



A. Height of aperture equal to or more than half the altitude of the 



entire shell. 



1. Axials less than eleven to the whorl, increasingly prominent 



toward the aperture Pyrifusus marylandicus 



2. Axials more than 11 and less than 15 to the whorl. 



a. Base of body whorl more or less excavated. 



i. External sculpture vigorous, spiral sculpture on body 



whorl not restricted to the base Pyrifusus vittatus 



ii. External sculpture subdued, spiral sculpture on body 



whorl restricted to the base. . . .Pyrifusus monmouthensis 



b. Base of body whorl obliquely truncated Pyrifusus cuneus 



3. Axials more than 15 in number Pyrifusus whitfieldi 



B. Height of aperture less than half the altitude of the entire shell. 



Pyrifusus elevata (?) 



Pyrifusus marylandicus n. sp. 

 Plate XVI, Pigs. 7-9 

 Description. — Shell rather short, fusiform, thin, fragile ; maximum 

 diameter falling a little in front of the median horizontal; whorls prob- 

 ably six or seven in all, closely appressed, broadly convex; body whorl 

 inflated, smoothly constricted at the base; axial sculpture manifested in 

 the shape of low, broad undulatory costae, approximately nine or ten to 

 the whorl, not very prominent even upon the periphery and evanescing 

 entirely in front of and behind it, but becoming increasingly prominent 

 toward the aperture and, on the final half turn, appearing as narrow but 

 very prominent ridges, rounded upon their summits, and separated by pro- 

 found troughs, the ridges abruptly evanescent in front of the appressed 

 posterior band and before reaching the base of the ultima ; spiral sculpture 

 uniform in general character over the entire external surface, the lira? 



1 Rept. U. S. Geol. Survey, Territories, vol. ix, p. 343. 



