DENTALIUM-EPISIPHON. 117 



concentric rings. Apex attenuated ; apical fissure very short. 

 (Sowb.*). 



Narrower than D. eburneum, more diaphanous, and of a reddish 

 color. This is a brightly colored, transparent shell, much narrower 

 in proportion than D. eburneum. (Sowb.*). 



Length 52, greatest diam. 4 mill, (from fig.). 



Subgenus EPISIPHON Pilsbry & Sharp, 1897. 



Small, very slender, rather straight shells, needle-shaped or trun- 

 cated, slightly tapering, thin and fragile, glossy and smooth, or at 

 least without longitudinal sculpture ; apex with a projecting pipe 

 or a simple orifice ; no slit, rarely a notch. 



Inhabitants of moderately or very deep water in the Mediterra- 

 nean, Atlantic, Gulf of Mexico and Pacific. 



The small accessory tube or pipe at the apex is frequently devel- 

 oped in most, perhaps all, of the species grouped here ; although 

 most young and many adult shells lack it. The majority of the 

 species are known by but few specimens, but in D. filum and D. in- 

 numerabile, of which we have seen a good many hundreds, the spe- 

 cific characters though not very conspicuous or strongly marked, 

 seem very constant. 



Key to species. 



I. Aperture oval, the tube laterally compressed ; salmon colored, 



innumerabile, p. 119. 

 II. Aperture circular. 



a. Shell decidedly curved, white or fulvous; length 18, 

 diam. 1-2 mill., longum, p. 120. 



a'. Shell nearly straight. 



b. Decidedly tapering, acicular, subreetum, p. 119. 

 b r . Subcylindrical, usually with an accessory apical 

 tube in adults, nearly smooth, 



sowerbyi, p. 117 ; filum, p. 118 ; fistula, p. 118. 



b". Upper part of tube encircled by deep, close-set 



grooves ; an apical tube developed ; length about 



13 mill., tornatum, p. 121. 



D. SOWERBYI Guilding. PI. 20, fig. 30. 



Shell small, nearly smooth, transversely indistinctly subplicatu- 

 late, the apex bearing a tube. Length 13 mill. (Gldg.'). 



Caribbean Sea. 



