DENTALIUM-RHABDUS. 113 



circular. Anal orifice circular, its edge in the type specimen jagged 

 from breakage, but apparently without true slit or notch. Length 

 31*5, diam. at aperture 1'6, at apex 0'5 mill. 



Off Mania, Ecuador, in 401 fms., bottom temperature 42'9 (U. 

 S. Fish Commission, Station 2792). 



No recent species known to us is so nearly straight as this. It is 

 smaller at the apex and straighter than D. watsoni, which seems to 

 be its nearest ally. D. innumerabile is another almost straight 

 species, but it is smaller, colored and compressed, and belongs to an 

 appreciably different group of species. D. rectius is like this in 

 texture, but is of course very much less slender. The unique type 

 is no. 122759, U. S. Nat. Mus. 



D. WATSONI Sharp & Pilsbry, n. sp. PI. 21, fig. 44. 



Shell very slightly curved, long, extremely slender, not much taper- 

 ing, thin, white; surface shining, wholly free from longitudinal 

 sculpture, the growth-lines fine and inconspicuous. Aperture cir- 

 cular, hardly oblique. Anal orifice small and circular, simple ; 110 

 slit or notch. 



Length 31, diam. at aperture 1'6, at apex 75 mill. 



Length 29'3, diam. at aperture 1'8 at apex 0'75 milL 



Off Tillamook Bay, Oregon, in 786 fms. (U. S. F. C., sta. 3346) ; 

 off San Diego, California (U. S. F. C., Sta. 2923). 



As straight as D. rectius Cpr., but very much more slender. It is 

 more curved than the closely allied D. cequatorium from off" Ecuador, 

 and slightly larger at the aperture. The specimens are but slightly 

 translucent, one being quite and the other almost opaque ; but they 

 are both dead shells, and may have been more transparent in life. 



Types are nos. 107702 and 107706, U. S. National Museum. It 

 is named in honor of the learned author of the ' Challenger' Report 

 on Scaphopoda and Gastropoda. 



D. RECTIUS Carpenter. PL 21, fig. 45. 



Shell almost straight, slender and long, attenuated toward the apex, 

 thin and fragile, bluish-white, somewhat translucent, .with some 

 opaque white flecks or rings, often encrusted near the aperture with 

 a reddish deposit. Surface very glossy, polished, growth-marks being 

 only faintly seen, and sculpture absent. Aperture not oblique, 

 almost circular, but the tube is a little compressed laterally ; per- 

 istome thin. Apical orifice small, circular, without notch or slit, 

 but from its extreme fragility the end is often nicked or broken. 



