106 
NATJTILOTDEA. 
Remarlcs. The following particulars regarding the history and 
affinities of the present genus are taken from the writings of 
Messrs. Meek and Worthen^ : — Although in some respects analo- 
gous to Risciies, M‘Coy, these shells differ from the typical forms of 
Fig, 15. 
CoeJooumtHux cariniferus, J. de C. Sowerby, sp., from the Carboniferous Lime- 
stone, Cork, Ireland. — A. Ventral or peripheral aspect of the base of the 
body-chamber (nat. size), showing at m, m, marks of the shell-muscles 
{m in all the other figures has the same meaning); p, in all the figures 
(exclusive of E) refers to the pitted and rugose surface of the muscular im- 
pressions B. Dorsal (internal) aspect of the same fragment : t, test ; il, 
dorsal lobe of a septum. C. Base of the body-chamber of a larger (? adult) 
specimen: t, test; cp\ groove. D. Reduced figure of a nearly perfect example 
of this species, from which the fragment lettered A and B was removed, 
as explained elsewhere in the text. E. Outline, much reduced in size, 
drawn from a cast of the interior of Xautilus pompUius : /, finely impressed 
lines left by the shell-muscle ; s. sutures of the septa. 
^ Geol. Surv. of Illinois, Palceont. vol. ii. 1866, p. 161. 
