CADULUS-DISCHIDES. 143 



a'. Moj-e slender or attenuated ; ventral outline convex ; dorsal 

 outline as a whole concave, not projecting beyond a chord 

 connecting the ends of shell, Section Gadila, p. 



Section Dischidks Jeffreys, 1867. 



Dischides Jkffr., Annals and Magazine of Nat. Hist. (3), xx, p. 

 251 (in text). 



Gadus " Rang," Deshayes, Descr. Anim. s. Vert. Bassin de Paris, 

 ii, p. 217, 1864, (in part) for G. parisiensis [=C. denticulatus Dh.], 

 G. bilabiatus [=C bifissuraUis Dh.], and G. brevis Dh. 



Shell rather slender, not much bulging ; apex cut into an anterior 

 and a posterior lobe by two deep lateral slits, one on each side. 

 Type C. (Dischides) j^olitus S. V. Wood. 



Distribution : Recent in both the Atlantic and Pacific ; Paris 

 Basin Eocene to Pliocene of Europe. 



Jeffreys describes the soft parts of C. politus as follows : 



Body whitish, gelatinous ; mantle rather thick, forming a collar 

 round the front opening of the shell ; captaeula issuing from within 

 the mantle, numerous, capable of so great an extension as to exceed 

 the shell in length ; stalks very slender ; terminal bulbs oval ; foot 

 cylindrical and narrow, protruded from the middle of the mouth as 

 from a sheath ; it is occasionally thrust out in a darting manner and 

 suddenly withdrawn, and so swiftly that the point of the foot could 

 not be observed ; the foot is usually curved towards the point ; 

 anal tube protruded beyond the narrower end or extremity of the 

 shell ; it consists of an outer and inner part, the latter being folded 

 to suit the slit on each side ; gills rather short, of a brownish color. 



Key to species of Dischides. 



I. Slender, but little contracted anteriorly, the length of shell 8 or 

 9 times its greatest diameter. 



a. Slits at apex narrow and deep ; tube contracting quite 

 noticeably and suddenly near aperture ; length 7'6 mill., 

 about 9* times the greatest diam., ^joZiiws. 



a'. Slits wide and triangular ; tube very little contracted to- 

 ward the aperture ; length 9*2 mill., about 8 J times the 

 greatest diam., belcheri. 



a". A shallow, rounded hollow on each side of apex ; tube 

 gently contracted at mouth ; length 8"2 mill., about 8i 

 times the greatest diam., prionotus. 



