Weller — Kiriderhook Faunal Studies. 117 



which increase in size somewhat rapidly towards the aperture ; 

 the greatest diameter of the type specimen, which is incom- 

 plete, 30 mm. The inner volutions subcircular in transverse 

 section, the outer one becoming remotely subtriangular, the 

 diameter of the whorl at the largest part of the shell, 18 or 

 20 mm. The lateral surfaces convex ; the dorsum rounded, 

 marked along the middle by a shallow groove. The dorso- 

 lateral angles ornamented by a single row of rather small, 

 moderately elevated, oblique nodes, whose outer ends are 

 directed backward; the nodes increase in size with the 

 growth of the shell, they being nearly obsolete upon the inner 

 whorls. The surface of the type specimen is smooth. 



Remarks. In its smooth surface this species is unlike most 

 of the species of the genus, but the type specimen is a cast, 

 and it is possible that the external surface of the shell was 

 marked by the usual revolving and transverse striae. 



PORCELLIA RECTINODA Win. 



This species was described by Winchell from the "yellow 

 sandstone " at Burlington, and although it has not been 

 observed, it is possibly a member of the Chonopectus sand- 

 stone fauna. Judging from the description it resembles P . 

 obliquinoda but is much smaller, the type specimen having a 

 maximum diameter of 15 mm. with the diameter of the outer 

 whorl at the aperture scarcely 5 mm.; it also differs from 

 P. obliquinoda in the more nearly circular section of the 

 whorls and by the transverse, rather than the oblique, direc- 

 tion of the nodes. Specimens from the Vermicular sandstone 

 at Northview, Missouri, have been compared* with this 

 species, though they are considerably larger. 



SCAPHOPODA. 

 Dentalium grand aevum Win. 



PI. VII. f. 6. 



" Shell rather large, perfectly straight and terete, or a 

 little compressed, tapering 1 mm. in 12 mm. near the larger 



* Trans. St. Louis Acad. Sci. 9 : 43. pi. o.f. 7. 



