469 
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? BANDONIS. 
SCHROEDEROCERAS? Banponis, Rem. (Unter. verstein. Diluvial- 
gescheibe, i, Pl. ili, Fig. 4). 
SCHROEDEROCERAS ODINI, Vern. (Geol. Russia, Pal., ii, Pl. 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 Odint 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. 8¢. 
SCHROEDEROCERAS DENCKELMANNI. 
LIT. CORNUARIETIS, De Vern. (Pal. Russia, Pl. xxv, Fig. 7). 
Lit. DENCKELMANNI, Rem. 
DIscOCcERAS DENCKELMANNI, Rem. (Zettsch. deutsch. geol. Gesell., 
XXXVill, 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 deep!y marked impressed zone. 
SCHROEDEROCERAS DAMESI. 
TrRocHoLiTes Damesi, Schroeder (‘‘Ceph. d. Untersil.,’’ Pad. 
Abh., Dames et Kayser, v, Pl. xxviii, Fig. 2). 
This shell was erroneously referred to Trocholites by Schréder, 
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 
