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produced by the mechanical effect of the proximity of the stiff wall 

 of the metanepionic substage. It would be extremely instructive to 

 make a number of such preparations and study comparatively the 

 amount and variability of this characteristic with relation to the 

 size of the umbilical perforation, its position, etc. 



SCHROEDEROCERAS ? EANDONIS. 



Schroederoceras ? Bandonis, Rem. ( Unter. verstein. Diluvial- 



gescheibe, i, PL iii, Fig. 4). 

 Schroederoceras Odini, Vern. (Geol. Russia, Pal., ii, PI. xxv, 

 . Fig. 8). 



This entirely smooth shell has rounded whorls, the ventro-dorsal 

 diameters in adults longer than the transverse. There are deeply 

 sinuous sutures with slight ventral lobes on the abdomen in the 

 neanic stage, and these are replaced by flattened saddles (if cor- 

 rectly figured) in the ephebic whorl. It is obviously, if the charac- 

 ters are correctly depicted, quite distinct from Schroed. teres. 

 These species agree in general aspect, but not in the form of whorl 

 of the coiled stages of growth, and differ also in the sutures and in 

 position of siphuncle and in the shape of the free whorl. 



In Odini there is no impressed zone on the free whorl, and 

 probably this was very slight in the neanic stage, as shown by 

 Verneuil's Fig. 8c. 



Schroederoceras Denckelmanni. 



Lit. cornuarietis, De Vern. (Pal. Russia, PL xxv, Fig. 7). 

 Lit. Denckelmanni, Rem. 



Discoceras Denckelmanni, Rem. (Zeitsch. deutsch. geol. GeselL, 

 xxxviii, 1886, p. 468). 

 This is a completely smooth shell with rounded and more 

 numerous whorls at the same size than in Schroederoceras angulatum 

 and a less deeply marked impressed zone. 



Schroederoceras Damesi. 



Trocholites Damesi, Schroeder (" Ceph. d. UntersiL," Pal 

 Abh., Dames et Kayser, v, PL xxviii, Fig. 2). 

 This shell was erroneously referred to Trocholites by Schroder, 

 if his figure is correct. The young has the large umbilical perfora- 

 tion, the large whorls and rapid increase by growth, as well as the 

 characteristic surface markings of this genus. The last whorl has 



