CLASS SCAPHOPODA 



This class Includes the marine mol- 

 lusks commonly known as tooth or elephant- 

 tusk shells. The crescent-shaped shells 

 taper In size and both ends are open. From 

 the larger end the foot is operated and 

 used for digging in mud or sand. The head 

 is not well defined but a radula is pres- 

 ent. The sexes are separate. There are 

 comparatively few species known but indi- 

 viduals exist in great numbers. 



Family Dentaliidae 



Foot of animal conical and pointed, 

 surrounded by a process like a wing-shaped 

 sheath, which in turn has a slit like a 

 break in a fold on one side. The shell 

 characters include more or less sculpture. 

 There is only one genus. 



GENUS DENTALIUM Linn6 1758 

 (TOOTH SHELLS) 



Shell a tube opening at both ends, 

 almost straight to curved, sculpture vary- 

 ing from faint indications to as many as 

 sixty prominent ribs. Often the senile 

 portion of the shell is smooth. There are 

 also frequently intermediate transverse 

 lines. The embryonic portion of the apex 

 (smaller end) is fragile and minute. It is 

 usually lacking in adult specimens. Usual- 

 ly there is a notch or slit in the smaller 

 or apical opening. 



The Dentaliums vary from needle- 

 like forms to heavy shells 5 inches in 

 length. Some are very fragile. The sur- 

 faces vary from chalky to porcellanous or 

 glassy. White is predominant but greenish, 

 reddish or yellowish species also occur. 

 They may be translucent, opaque, dull or 

 with glistening surfaces. 



The animal conforms in shape to the 

 shell it occupies. The cylindrical foot 

 may be protruded or almost completely with- 

 drawn. Tentacles or eyes are absent. Fora- 

 minlfera and other minute organisms are 

 supposed to be caught by a cluster of 

 thread-like appendages Just back of the 

 mouth. The sexes are separate. 



DENTALIUM ANTILLARUIJ Orbigny. Shell small, 

 moderately curved; tip when present point- 

 ed and slender; surface white; opaque, with 

 bands of translucent gray; texture hard, 

 porcellanous but not shining; nine primary 

 ribs, also secondary ribs; wide, shallow 

 apical notch usually on convex side. Length 

 22 mm., without tip. 



This very variable form is the com- 

 monest shallow water species in the West 

 Indies and adjacent waters. The writer 

 dredged it in shallow water off Tiger Key 

 and Lossman's River, Florida, in the Gulf 

 of Mexico. 



PI. 55, Fig. 18 



Miami, Florida to the West Indies 



DENTALIUM CALLITHRIX Dall. Shell gradually 

 increasing in diameter; white porcellanous 

 but not shining; nine major ribs, as many 

 as three secondary ribs between these. The 

 sculpture is sometimes not continuous along 

 the shell. Length 24-38 mm. 



A deep-water shell; sometimes taken 

 upon the beach at Sanibel. 



PI. 63, Fig. 10 



PI, 55, Fig. 21 



Cape Hatteras, North Carolina to 



Florida; Brazil 



DENTALIUM CALLIPEPLUM Dall. Strongly and 

 evenly curved like a scimitar; ivory or 

 creaun white, sometimes salmon tinted on tip; 

 highly polished; no sculpture; a faint 

 shallcw notch. Length 62 mm. Range 25-169 

 fathoms. 



PI. 63, Fig. ISb 



Gulf of Mexico; West Indies 



DENTALIUM CARDUUS Dall. Sixteen narrow 

 longitudinal ribs; elevated transverse rib- 

 lets producing a rasp-like surface; pure 

 white, not polished. Length 77-87 mm. 

 Range 100-338 fathoms. 



PI. 63, Fig. 3 



Bahamas; St. Lucia. 



DENTALIUM EBOREUM Conrad (D. matura Dall). 

 Color salmon pink or yellowish; curved, 

 slender, thin but strong; surface highly 

 shining, vitreous but often with milky 



71 



