21 C> ATURIA, DISCITES. 



cles were extended radially from the head, somewhat like those 

 of a sea anemone ; but each pair had its definite and different 

 direction, which was constantly maintained ; thus one pair of 

 tentacles was held pointing directly downwards, two other pairs, 

 situate just before and behind the eyes, were held projecting 

 obliquely outwards and forwards, and backwards respectively, as 

 if to protect the organs of sight.* 



X. STENOMPHALUS, Sowb. PL 99, fig. 509. 



Shell like N. PoinpiHux. but very narrowly umbilicated. 



Eastern Archipelago. 



I scarcely think this deserves to be separated from A'. Pom- 

 pilius ; the very narrow umbilicus is exposed simply because the 

 callous deposit has not spread sufficiently to cover it; there is 

 no excavation around the umbilical region, as in the following 

 species. 



X. MACROMPUALUS, Sowb. PL 99, fig. 510. 



Umbilical region excavated, but with rounded margin ; umbili- 

 cus wide, exposing the whorls. 



New Caledonia, etc. 

 X. i MBTUCATI s. Lister. PL 99, fig. 511. 



Surface smooth' to spirally striate ; umbilical region wide, 

 angularly excavated, umbilicus wide, showing all the whorls. 



Solomon Islands, New Ireland, etc. 



The stria' are not constant; I have therefore reunited with 

 this species N. %crobicul(ttus of Dillwyn and Gould and N. per- 

 foratux, Conrad. 



Subgemis Aturia, l>romi. 



Sutures of septa with a deep lateral lobe; siphuncle on the 

 concave or inner side of the shell, large, continuous, like a suc- 

 cession of funnels. 



Four species. Eocene. N.America; Eurofx- ; I ml la.' 

 A. ZICZAC, Sby. PL 9S. figs. ;>():>. ;"><>:; . Eocene. //////*/,. 



Suligi'iiii.- Discites, Mc<'<.\. 



Whorls all exposed : last chamber sometimes produced. 

 Five species. L. Silurian I' 



* Mosely, Notes by a Natural isl on the Challenger, ,"-><;. 



