44 DENTALIUM-ANTALIS. 



under which name the species is generally known in American col- 

 lections. Had he compared with D. entalis, the identity of the two 

 would no doubt have been recognized. There is no difference, not 

 even varietal, between English and Maine specimens. D. striolatum 

 or Entalis striolata of Jeffreys, Sars and Watson is D. occidental 

 Stimp. D. striolatum of Risso is D. vulgare. 



There is great latitude of opinion regarding the limits of the species 

 entalis; some conchologists holding occidental, agile and pretiosum 

 as merely varieties of the Linnsean species. The following variations 

 have been named : 



Var. infundibulum Jeffr. Shorter and less cylindrical, being pro- 

 portionally wider toward the mouth. Loch Fyne (Jeffr., Brit. Conch., 

 v, p. 197). Var. anulata Jeffr. Narrower and more regularly 

 cylindrical, ornamented with white ring-like marks of growth (Jeffr., 

 Brit. Conch., iii, p. 192). 



Var. ORTHRUM Watson. 



Rather long and straight, and sharply striate toward the apex, 

 thus combining the form of D. agile with the sculpture of D. abys- 

 sorum. 



Setubal, 470 fms. ; Fayal, Azores, 450 fms. ; Prince Edward Island , 

 140 fms. (Challenger) ; Gulf of Gascony (Hirondelle). 



D. entalis var. orthrum WATS., Journ. Linn. Soc., Zool., xiv, p. 

 512 (1879); Challenger Rep., p. 6. DAUTZENBERG, Mem. Zool. 

 Soc. France, iv, p. 609, 617. 



D. PRETIOSUM < Nuttall ' Sowerby. PI. 13, figs. 1, 2, 3. 



Shell rather long, moderately curved and solid ; opaque white, 

 ivory-like, often with some faint dirty buff rings or tinted with that 

 color at the smaller end. Sculpture of fine, irregular growth-striae 

 and occasional deeper grooves caused by interrupted growth ; usu- 

 ally with no longitudinal sculpture in adults, but sometimes showing 

 longitudinal strise toward the apex, the young with numerous small 

 riblets (but in southern specimens the longitudinal sculpture is more 

 persistent). Aperture circular, oblique, the peristome thin. Apex 

 rather broadly truncate, the orifice small, oblong, continued in a 

 short notch on the convex side ; often having a narrow raised rim. 



Length 55, diam. of aperture 5, of apex 2 mill. (Washington). 



Length 41, diam. of aperture 5, of apex 2'7 mill. (Brit. Columbia). 



Length 41, diam. of aperture 3'8, of apex 1-5 mill. (Cerros I.). 



West coast of America from Sitka, Alaska, to Cerros L, Lower Cali- 

 fornia. 



