EAST AMERICAN SCAPHOPOD MOLLUSKS. 11 



The genus has been divided into two "sections," according to 

 the presence or absence of apical lobes, but the value of the sub- 

 divisions may be questioned. They are: 



Apex with slits or lobes Siphonodentalium a. s., page 88. 



Apex simple Pulsellum, page 92 . 



Genus CADULUS Philippi, 1844. 



1844. Cadulus Philippi, Enum. Moll. Sicil., vol. 2, p. 209. 



Type. — C. ovulum Philippi. (Mediterranean.) 



Shell scupltureless, smooth, polished, of circular or oval section. 

 More or less arcuate, with a greater or lesser swelling or bulge near the 

 middle or between the median portion and the aperture. Aperture 

 usually somewhat contracted and never the section of greatest 

 diameter of the shell. Apical characters vary from simple to two 

 or four deeply or slightly cut notches. 



The division of Cadulus into subgenera of doubtful value finds an 

 excuse only in the aid it offers in grouping conveniently a large num- 

 ber of species of slight diagnostic features. Possibly the value of 

 Polyscliides from a biologic point of view may be less questioned as a 

 subgenus distinct from what is accepted as typical Cadulus, but the 

 others are rather artificial. The follo^ving is the order of subdivision 

 offered by Pilsbry and Sharp with the addition of Platyschides: 



Apex with two prominent slits Dischides. 



Apex \\-ith four prominent slits leaving four prominent triangular lobes, 



Polyschides, page 96. 



Apex with four very shallow notches leaving four wide lobes Platyschides, page 104. 



Apex not slit or notched. 



Small obese forms Cadulus s. s., page 141. 



Slender forms Gadila, page 130. 



The subgenus Dischides characterized by two slits in the apex is 

 as yet unknown from the faunal areas under consideration. 



LIST OF THE EAST AMERICAN SCAPHOPODS. 



Denfalium (Dentalium) laqueatum Verrill 1885, page 23. 

 Dcntalium (Dentalium) laqueatum laqueatum Verrill 1885, page 24. 

 Dentalium (Dentalium) regularc, new subspecies, page 26. 

 Group of D. texasianum: 



Dentalium (Dentalium) texasianum Philippi 1848, page 27. 



Dentalium (Dentalium) texasianum texasianum Philippi 1848, page 28. 



Dentalium (Dentalium) texasianum cestum, new subspecies, page 29. 



Dentalium (Dentalium) texasianum rioense, new subspecies, page 29. 



Dentalium (Dentalium) gouldii Dall, 3889, page 29. 



Dentalium (Dentalium) gouldii gouldii Dall, 1889, page 30. 



Dentalium (Dentalium) gouldii portoricense, new subspecies, page 30. 



Dentalium (Dentalium) gouldii colonense, new subspecies, page 31. 



Dentalium (Dentalium) rebeccaense, new species, page 31. 



Dentalium (Dentalium) obscurum Dall, 1890, page 32. 



Dentalium (Dentalium) carduus Dall 1889, page 33 

 157582°— 20 2 



