CADULUS-POLYSCHIDES. 147 



This group differs from Siphonodentalium in having the tube con- 

 tracted toward the aperture; from Dischides in the greater number 

 of terminal lobes, and from Cadulus in the presence of slits at the 

 apex. The typical forms have four teeth, dorsal and ventral, and 

 on each side ; in a few species the apex is differently incised, hav- 

 ing two symmetrically placed side-slits as in Dischides, deeper than 

 those above and below. C. dalli Pilsbry & Sharp from off western 

 Patagonia, and C. parisiensis (Deshayes) from the Parisian Eocene 

 represent this type, which is about intermediate between Polyschides 

 and Dischides, if not actually nearer the latter group. 



Immature specimens have the characters of Siphonodentalium; and 

 when the apical lobes are broken off the shell is like the Gadila or 

 Helonyx manifestations of Cadulus. 



Polyschides species of the typical quadridentate form appear 

 numerously in the Eocene, together with species of the type of 

 C. dalli and of Dischides. 



Key to Species. 



I. Shell slowly tapering, hardly inflated, the apertural contrac- 

 tion slight and short ; apex large, cut into 4 bevelled teeth by 

 4 subequal slits; length 62-! mill., about 7 times the greatest 

 diameter. 



a. West Atlantic and Gulf of Mexico species, 



tetraschistus, quadridentatus, incisus, p. 148. 

 a'. Californian species, quadrifissatus, p. 150. 



II. Shell quite noticeably or strongly inflated, with marked con- 

 traction toward aperture ; apex 4-slit or notched ; known spe- 

 cies West Atlantic. 



a. Small, moderately swollen, fusiform, with a long, gentle 

 taper toward each end ; teeth large ; length 5 to 5.6 

 mill., 5? times greatest diam., tetrodon, p. 151. 



a'. Larger, moderately swollen anteriorly, attenuated poste- 

 riorly, circular in section throughout; length 7 10 

 mill., 6 times greatest diam., more or less ; 4 short teeth, 



carolinensis, p. 152. 



a". Large and stout, the greatest inflation at the anterior 

 third ; aperture broad-elliptical ; 4 rounded apical teeth ; 

 length 15 mill., about 4J times the greatest diam., 



grandis, p. 154. 



