﻿4G6 



tinct just before the whorl becomes free on the last quarter of the 

 fifth volution (Fig. 2). 



The nepionic stage of this species is given in Figs. 6-7, PL xiv. 

 The advent of the hyponomic sinus can be seen in the lines of 

 growth of the metanepionic substage in the front view, Fig. 6. The 

 umbilical perforation is larger than it appears to be in the side view, 

 Fig. 7, because it is in part overlapped by the inward growth of 

 the umbilical zones of the paranepionic volution. 



The lines of growth are entire and very fine lines on the anane- 

 pionic and metanepionic substages, and there are no longitudinal 

 ridges. The sides are convergent and rounded, and the abdomen 

 is rounded and narrower than the dorsum in these substages. At 

 the beginning of the paranepionic the abdomen becomes suddenly 

 flattened, the sides also tending to become flatter and the whorl 

 spreads laterally very fast, the venter becoming wider than the 

 dorsum. Slight crenulations also appear, and in consequence of 

 these faint longitudinal lines may be seen with a magnifier. 



Regularly spaced transverse lines are first noticeable in the 

 paranepionic forming the forward edges of broad laminae on the 

 surface and having finer lines of growth between them, as in Fig. 10, 

 PI. xiv. 



The septa in this substage are deeply concave and have broad 

 ventral saddles divided by narrow V-shaped central ventral lobes, 

 as in Fig. 10, PI. xiv. There are shallow lateral lobes and dorsal 

 lobes in the contact furrow. 



The siphuncle is propiodorsan in this substage as given in Fig. 9, 

 but was not seen in earlier ages. It is slightly nearer the dorsum in 

 the succeeding stages of development of this specimen. 



A distinct dorsal furrow appears in this shell in the early part of 

 the paranepionic and deepens until replaced and enlarged by the 

 contact furrow. Contact takes place upon the area of the scar, but 

 not on the dorsal side of this area. I was not able to define the ex- 

 act line of contact because the apex had been slightly fractured in 

 making the preparation, but it was quite clear that contact did not 

 occur upon the dorsum of the ana- nor metanepionic substages as it 

 does in Trocholites. The involution is greater and the contact 

 furrow deeper in the ananepionic substage, where it begins, than 

 at any subsequent substage, as shown in Fig. 8, PI. xiv. 



In the meta- and paraneanic substages the more prominent lines 

 of growth described above on the edges of the broad bands become 



