142 CADULUS. 



Genus CADULUS Philippi, 1844. 



Includes Cadulus Phil., Gadila Gray, Gadus auct., Helonyx 

 Stimp., Dischides Jeffr., Loxoporus Jeffr., Polyschides P. & S. 



Tubular, circular or oval in section ; somewhat arcuate ; varying 

 from cask-shaped to acicular ; more or less bulging or swollen near 

 the middle or above, contracting toward the aperture. Surface 

 smooth or delicately striated. 



The genus Cadulus, as we. use that term, contains species of a 

 great variety of shapes, and with various apical modifications, but 

 having in common an inflated bulging shell which contracts more or 

 less in caliber near the aperture as well as posteriorly. It is this 

 anterior constriction which separates Cadulus from Siphonodental- 

 ium. 



In some species of all the sections of the genus, a circular rib is 

 developed within the apical orifice, while others lack it. This struc- 

 ture is not, therefore, characteristic of the typical division only, as 

 some authors have claimed. 



The subdivision of Cadulus by conchological characters (and 

 there are as yet no adequate data upon the soft anatomy), is attended 

 with difficulties; but as the size of the genus and the heterogeneous 

 nature of its contents render some subdivision a convenience, the 

 following scheme is offered. 



The recognition of Gadila is an expedient of doubtful utility, for 

 there are no very definite features separating it from the typical 

 forms of Caduhts. The other sections are probably natural groups, 

 although when the teeth are broken off, not an unusual accident, 

 their differential characters are no longer apparent. It is hardly 

 necessary to warn the investigator against this pitfall ; but we may 

 perhaps be allowed to beg indulgence lest we may not in every case 

 have avoided it ourselves. 



Key to sections of Cadulus. 



I. Apex with slits or notches. 



a. Apex with two lateral slits only, Section Dischides, p. 143. 

 a'. Apex with four or more slits, Section Polyschides, p. 146. 

 II. Apex entire, unslit. 



a. Obese ; both ventral and dorsal outlines convex and project- 

 ing beyond a chord connecting the adjacent lip edges, 



Section Cadulus s. s., p. 



