328 American Seashells 



Cadulus quadridentatus Dall Four-toothed Cadulus 



Figure 69b 



North Carolina to both sides of Florida and the West Indies. 



5 to 10 mm. in length, swollen behind the aperture. Apex with 4 well- 

 defined slits. In cross-section the shell is roundish. Commonly dredged from 

 3 to 50 fathoms. 



Subgenus Gadila Gray 1847 

 Cadulus mayori Henderson Mayor's Cadulus 



Southeast Florida. 



3 to 4 mm. in length, swollen just anterior to the middle of the shell. 

 Apical opening % the size of the aperture and usually has i or 2 callus rings 

 within the opening. Fairly common from 1 6 to 1 00 fathoms. 



family DENTALIIDAE 



Shell with the greatest diameter at the aperture. Foot conical and with 

 epipodial processes. Median tooth of the radula twice as wide as long. 



Genus Dentalium Linne 1758 



The shell is an elongate, curved tube open at both ends, and somewhat 

 resembles an elephant's tusk. The diagnostic characters are the type of sculp- 

 turing (ribs, riblets and circular threads or incised lines), the form of the 

 apex, the degree of curvature, the size and thickness of shell and the position 

 and form of the apical slit. The ten or so subgenera are nebulous in charac- 

 ter and definition and one should consult the works of J. B. Henderson, 

 H. A. PUsbry and W. H. Dall. 



Subgenus Dentalium s. str. 

 Dentalium laqueatum Verrill Panelled Tusk 



North Carolina to south Florida and the West Indies. 



I to 2/4 inches in length, thick-shelled and dull-white in color. Apex 

 sharply curved; anterior % of shell slightly arched. 9 to 12 strong, elevated, 

 primary longitudinal ribs with equally spaced, concave intercostal (space 

 between ribs) spaces. Ribs fade out at the anterior third. There are fine 

 reticulations over the entire shell. A supplemental tube is present in the 

 young shells. Abundant in sandy mud from 4 to 200 fathoms. 



