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litse, with very broad whorls quite similar to those of his T. con- 

 tractus. 



Trocholites depressus. 



Clymenia depressa, Eichw. {Leth. Ross., PL 1, Fig. 5). 



Troch. depressus, Schroder {Ceph. d. Untersil., Pal. Abt., Dames 



et Kayser, v, heft 4, PL i, Fig. 4). 

 Trocholites macrostoma, Schroder {Ceph. d. Untersil., Pal. Abt., 



Dames et Kayser, v, heft 4, PL i, Fig. 1). 

 Troch. contractus, Schroder {ibid., PL i, Fig. 2). 



Excessively broad whorls and deep umbilici but no lateral zones. 

 Living chamber about one-half volution in length according to 

 Schroder's drawings. Schroder also describes the following species : 



Troch. orbis, Schroder {ibid., PL i, Fig. 23). 



" macromphalus, Schroder {ibid., PL i, Fig. 5). 

 " soraviensis, Schroder {ibid., PL ii, Fig. 1). 



Troch. remelei, Schroder {ibid., p. 18), was described as T. in- 

 cong? uus hy Ax\g. et Lindst. {Frag. Sil., PL ix, Figs. 15-18), and this 

 has a living chamber not quite one-half a volution in length. His 

 Troch. dame si {ibid., PL v, Fig. 2) shows sculpturing and form of 

 the young which appears to place it in the genus Schroederoceras 

 rather than in Trocholites and it has been referred to that genus. 



Trocholites circularis, Mill, et Dyer, of the Cincinnati group of 

 the Hudson river, is probably a distinct species. The type is in the 

 Museum of Comparative Zoology. This has an aperture like that 

 of T. ammonius and length of living chamber as in that species 

 about one-half of a volution. The whorls are not so stout as in 

 ammonius, the sides being slightly compressed, the abdomen nar- 

 rower than the dorsum. 



Trocholites dyeri, n. sp. 



This is a form in the Dyer collection from the Cincinnati group, 

 having a form of whorl broader and quite like that of T. ammonius, 

 but with a longer living chamber and distinct aperture. 



The living chamber is considerably over one-half of a volution 

 in length and the lateral and ventral edges of the aperture are flar- 

 ing like the mouth of a trumpet. This gives extraordinary promi- 

 nence to these parts and especially to the hyponomic sinus. The 

 umbilici were not seen, but are probably deeper than in T. ammo- 



