459 
Trocholites, but this is not sustained by closer approximation in the 
early stages. The nepionic stage has whorls which depart more 
widely from the trocholitean form of the same age than the later 
stages of growth. 
The umbilical perforation is large, the whorls are few in number 
and increase less rapidly by growth and change more in form than 
in Trocholites, the sutures are more sinuous, the siphuncle is not 
so close to the dorsum, the apertures narrower in transverse and 
longer proportionately in ventro-dorsal diameters and have deeper 
narrower hyponomic sinuses, the living chambers are much shorter, 
varying, so far as known, from less than one-fourth of a volution to 
somewhat more than one-half of a volution, and the size is very 
much greater at the same age in all dimensions and there are fewer 
whorls. 
The resemblances consist in the surface ornamentation, which, 
although much coarser, is similar to that of Trocholites. 
But even here the deep V-shaped dorsal sinus found in some 
species is quite distinct. The aspect of the neanic stage before the 
whorl acquires the flattened abdomen and sides is similar, but this 
likeness becomes of less. importance when the younger nepionic 
stage is considered. The ananepionic substage may possibly have 
very fine straight transverse striations, which are not usually visible, 
but it is apparently smooth as seen in my specimens and in the 
figures given by others.* The metanepionic stage has strong trans- 
verse bands of growth with finer strize on the surface of the bands. 
The borders of the bands are prominent and crenulated, the crenu- 
lation being due to short longitudinal depression and intermediate 
folds that occupy the edges of the bands and are discontinuous be- 
tween them. 
The costations also begin to appear in this substage, and these 
are in some species apparent as obscure folds on the casts. These 
are distinct from the bands of growth being less numerous on the 
surface and more widely separated. ‘The crenulations disappear 
subsequently probably before the completion of the second whorl, 
but there are often a few continuous longitudinal raised lines per- 
ceptible on the centre of the venter and near the umbilical shoulders. 
The cyrtoceran form is retained longer in the nepionic stage than 
in Trocholites and the change to the gyroceran curve that brings 
* See Schroeder's figure of Schroederoceras ( Troch.) Damesi, Pal. Abh. v, Pl. xxviii, Fig. 2a. 
