458 Trans. Acad. Sci. of St. Louis. 



jeffersonensifi may be distiaguislied b}^ its smaller size, its less 

 flaring aperture, its more flattened dorsum and its much more 

 regular transverse co8tae. 



Tropidodiscus cyrtoltes (Hall). 



Plate 2, Jig- 29. 



Bellerophon cyrtolites Hall,, 13th Rep. N. Y. St. Cab. Nat. Hist., p. 107, 

 (1860) ; Bellerophon cyrtolites Win., Proc. Acad. Nat. Sci. Phil., p. 426, 

 (1862); Bellerophon cyrtolites Win., Proc. Acad. Nat. Sci. Phil., p. 18, 

 (1863); Bellerophon cyrtolites Win., Proc. Acad. Nat. Sci. Phil., p. 131, 

 (1865) ; Bellerophon cyrtolites M. & W., Geol. Surv. 111., vol. 2, p. 160, 

 pi. 14, flgs. 8a-b, (1866); Bellerophon cyrtolites Win., Proc. Am. Phil. 

 Soc, vol. 11, p. 257, (1870); Bellerophon cyrtolites Herriclj, Bull. Sci. 

 Lab. Den. Univ., vol. 3, p. 86, pi. 2, flgs. 27, 29, pi. 8, flgs. 20, 21, pi. 9, 

 flgs. 29, 31, (1888); Tropidodiscus cyrtolites Weller, Trana. Acad. Sci., 

 St. Louis, vol. 9, p. 89, pi. 6, flgs. 8-9, (1899). 



This species is one of the rarest members of the Glen Park 

 fauna, but the specimens observed are indistinguishable from 

 those occurring elsewhere in the Kinderhook formations. 

 The species was first described from the Kinderhook goniatite 

 bed at Rockford, Indiana, but it has been recognized in the 

 Waverly beds of Ohio, in the Marshall beds of Michigan, and 

 the " yellow sandstone " at Burlington, Iowa. In the collec- 

 tions of Walker Museum the species is represented by speci- 

 mens from the Northview sandstone of Webster County, Mis- 

 souri, and from the Chouteau limestone of Pettis County, 

 Missouri. Wherever the species has been observed by the 

 writer it is rare, yet it is one of the forms having a wide geo- 

 graphic distribution. The species has no known near relative 

 in the Hamilton faunas of the east, but it is cogeneric with 

 Bellerophon curvilineatus Con., of the eastern Onondaga 

 fauna. 



Naticopsis paucivolutus n. sp. 



Plate 2, figs. 27-28. 



Description. Shell small, ventricose, imperforate, with 

 two and one-half or three volutions which increase rapidly in 

 size. Spire low, apical angle 80°-85°, the suture strongly 

 impressed and regularly increasing in depth towards the 

 aperture, outer volution very much larger than those within, 

 its height nearly three-fourths the entire height of the shell. 



