﻿618 



Fig. 7. Side view of the apex of the conch in another preparation showing the 

 same substages and a part of the paranepionic substage. 



Fig. 8. Diagram of the exterior of the ananepionic substage. This also shows 

 the position of caecum and septum of the first living chamber of the metanepionic 

 in the interior, and supposed outlines of aperture of ananepionic substage. In 

 the ananepionic substage the apex of the conch is empty and this diagram there- 

 fore gives the erroneous impression that the caecum and first septum belongs to 

 this substage, whereas it is obviously a part of the metanepionic substage. 



Fig. 9. Front view of the same showing outline of aperture of ananepionic 

 substage and also the position and size of the primitive siphuncle or caecum first 

 septum of the metanepionic substage.* 



Fig. 10. Diagram of same and exterior of first living chamber of the metane- 

 pionic substage showing change of position towards the venter of the siphuncle in 

 the septum of the second living chamber of same substage. 



Fig. 1 1. Front view of the same with siphuncle of the same. 



Fig. 12. Side view of the exterior of two first substages and supposed aperture, 

 with the siphuncle and first septum of the paranepionic substage. The siphun- 

 cle, it will be observed, changes again towards the centre between these two 

 septa. 



Fig. 13. Front view of the same showing approximate outline of aperture 

 taken from actual outline of shell in section at the constriction terminating 

 the metanepionic substage. This shows the nephritic character in the volution 

 and exhibits also the dorsal furrow beginning to form at this early age before 

 the gyrcceran curve begins. This drawing is placed so that the observer can 

 compare the outlines of the shell at this substage with that of the later age of 

 the paranepionic substage in Fig. 1. In the latter the siphuncle has assumed the 

 permanent position of the ephebic stage below the centre. 



* Figs. 9-11 should have been reversed to accord with the side views and with the other 

 figures. 



