I 



DENTALIIDyE. 455 



Sub-gen. tugali, Gray. 



Shell white, oblong, surface cancellated ; aperture with the 

 margin creuulated. 



cariuatus, A. Adams. elegans. Gray. 



cicatrosus, A. Adams. osseus, Gould. 



cinereus, Gould. radiatus, A. Adams. 

 decussatus, A. Adams. 



Fam. DENTALIID^E. 



Lingual ribbon wide, ovate, rachis single-toothed, im- 

 cini single, flanked by single, unarmed plates. Body 

 elongated ; head rudimentary, without tentacles or eyes ; 

 mouth with cirrhated lips. Mantle circular, anteriorly 

 thick and fleshy, investing the fore part of the body; gills 

 two, symmetrical. Foot rudimentary, small, conical, 

 with two symmetrical side-lobes, and an attenuated, hollow 

 base, communicating with the stomach. 



Operculum none. 



Shell elongate, or elevately-conical, surface smooth or 

 longitudinally striated ; vertex perforated, posteriorly in- 

 clined ; aperture circular, not constricted. 



According to the observations of Clark, the blood of 

 these animals is red, the sexes are united, and the gills 

 are posterior to the heart. Should these views be con- 

 firmed, the family must be removed from the Prosobran- 

 chiate division of Mollusks. The most usual way of re- 

 garding the Dentaliid(B has been to consider them as 

 elongated Fissurella, with the eyes and tentacles wanting, 

 and the foot rudimentary and tubular; the perforated. 



