DENTALIIDiE HI 



Class SCAPHOPODA, 



Shell a hollow cylinder, open at both ends. Head rudimentary ; 

 foot vermiform, lobulate ; nervous sj^stem simplified, resembling 

 that of the lamellibranchs. 



The shells of the Scaphopoda are immediately distinguishable 

 from those of all other living mollusks by external form., being- 

 straight or slightly curved tubes, without spire. 



Family DENTALIID.^. 



Shell tubular, symmetrical, curved, open at each end, attenu- 

 ated posteriorly ; surface smooth or longitudinally striated ; 

 aperture circular, not constricted. 



Animal attached to its shell near the posterior anal orifice ; 

 head rudimentary, eyes 0, tentacles ; oral surface fringed ; 

 foot jDointed, conical, with symmetrical side-lobes, and an atten- 

 uated base, in which is a hollow communicating with the 

 stomach. Branchias 2, symmetrical, posterior to the heart; 

 sexes separated. 



The tooth-shells are animal-feeders, devouring foraminifera 

 and minute bivalves ; they are found in sand, or mud, in which 

 the}^ usually bury themselves. 



Sars divides the Scaphopoda into two orders : I think that 

 his distinctive characters are barely sufficient to be used in a 

 subfamily sense. 



Subfamily DENTALIINjE. 



Posterior aperture of the shell entire or with a ventral slit, 

 provided with a supplementary tube. Foot trilobate. Edge of 

 the lateral plates of the radula indistinctly dentate. (Order 

 Scaphopoda, Sars.) 



Dentalium, Linn., n58. 



Distr. — 15 sp. Universal. D. elephantinum, Linn, (ciii, 98). 



Animal with a short foot, anteriorly thickened and tripartite. 

 Shell tube-like, gradually tapering posteriori}', longitudinally 

 ribbed, margin of the aperture sharpened, posterior end with an 

 internal, slightly projecting tube, which is provided with a dorso- 

 ventrally elongated opening, the outer layer having a very slight 

 emargiuation dorsally and ventrally. 



" The Dentalium burrows in the sand by means of its conical 

 foot, in a slanting direction ; the narrow end is, of course, upper- 

 most, and is kept in communication with the air or water for the 

 purpose of respiration. It feeds on foraminifera and other 



