156 CADULUS. 



Another specimen, figs. 21,22, 23, measures, length 1T2, diam at 

 aperture 1-66 x 1-66, at greatest 2*22 x2'22, at apex 0'72 x 0*8 mill. 



West Coast of Patagonia at Fish Commission Station 2,783, S. lat. 

 51 2', Ion. 74 8', in 122 fms. mud, bottom temp. 47; Sta. 2,784, 

 S. lat. 48 41', Ion. 74 24' in 194 fins., temp. 51 ; and at other 

 stations in 258 and 449 fms. ; Magellan Strait in 369 fms., bottom 

 temp. 46. 



Comparatively few specimens show the terminal teeth ; they are 

 usually broken off, leaving only the two deeper lateral slits visible. 



The apical slitting, when preserved, is on the plan of 0. parisien- 

 sis (Desh.) in having two deeper lateral slits, but the lobes of the 

 anterior and posterior segments are fewer. None of the Atlantic 

 species with denticulate apices are like this, so far as we can judge 

 by what we have seen and the published figures. The specimen 

 drawn in figs. 21-23 is more contracted towards the mouth than 

 the larger one figured, and is quite circular in section, the other 

 being a mere trifle flattened. C. dalliis more inflated than C. quad- 

 ridentatus or quadrifissatux. 



Types are No. 123,746, U. S. Nat. Mus., from Station 2,783 ; the 

 smaller specimen figured is one of No. 122,736. The specimens 

 from Magellan Strait are not so large, two measuring, a, length 9, 

 greatest diam. 1'8 mill. ; b, length 10*7, greatest diam. 1-8 mill. 



Section CADULUS Philippi, 1844. 



Cadulus PHIL., Enum. Moll. Sicil., ii, p. 209. Type Dentalium 

 ovulum Phil. 



Shell somewhat cask-shaped, short and obese, conspicuously swol- 

 len in the middle, tapering rapidly toward both ends : convex on 

 all sides, though less so dorsally. Aperture with simple, thin peri- 

 stome; anal orifice comparatively large, with simple edge, con- 

 tracted by a wide circular callus or ledge just within the opening. 



Cadulus in the restricted sense comprises the short, obese forms, 

 in which no side of the shell is really concave, although* the dorsal 

 is less convex than the other contours, and the apical orifice is con- 

 tracted by a conspicuous callous ring just within the edge. This cal- 

 lus is also developed in many species of Polyschides, Gadila, etc., but 

 in these it is situated further within and is a comparatively feeble 

 structure. 



The species now known are all Mediterranean and North Atlan- 

 tic, and are all quite small. This is, geologically, the latest in ap- 

 pearance of the several subordinate groups of the genus. 



