226 



" Shell involute, volutions apparently one and a half, coiled closely on 

 the same plane but without embracing, strongly compressed on the venter 

 and dorsum and increasing very slowly in the ventro-dorsal diameter, but 



Fig. 16. Eurystomites plicatus. Outline of a longitudinal section through the 



same specimen, showing the shape and position of the siphuncle, and 



the apparent decollation of the earlier volutions. Natural size. 



expanding and widening rapidly at the sides, which are rounded and 

 gibbous, the outline of a transverse section of the chamber of habitation 

 near the aperture being broadly reniform, with the lateral diameter about 

 three times greater than the dorso-ventral, and the dorsum impressed by 

 a shallow and rather narrow furrow of contact : umbilical perforation 

 large and deep. 



"Surface marked with rather broad, low, rounde(^, flexuous, transverse 

 plications, and crowded strise parallel to the plications, both between and 

 upon them. 



" A longitudinal section through the centre of one of the specimens 

 shews that the cut edges of the concave septa are about two millimetres 



