CADULUS-DISCHIDES. 145 



used. There is a good deal of doubt about Philippi's D.pusillum; 

 so much that in the absence of a sufficient diagnosis it need not pre- 

 judice the use of Searles Wood's name polita, unmistakably fixed 

 as it is by a sufficient diagnosis and good figures. 



C. BELCHERI Pilsbry & Sharp, n. sp. PI. 26, figs. 84, 85, 86, 87. 



Shell small, moderately arcuate but the bend mainly posterior, 

 tapering, slightly swollen above the middle, and thence a very little 

 contracted to the aperture. Thin, translucent whitish, slightly 

 flecked with opaque posteriorly. Smooth and glossy, growth-strise 

 being hardly apparent under the lens. Aperture nearly circular, 

 but a trifle shorter than wide, the peristome oblique, thin. Anal 

 end bilabiate, with a wide triangular fissure on each side. 



Length 9*2, diam. at aperture '95 x I/O ; at greatest girth 1*05 x 

 1-08 ; at apex 0*4 x 0'4 mill. 



North Pacific (Sir E. Belcher!). 



Less abruptly contracted anteriorly and with more open lateral 

 slits than 0. politus AVood. This is the form mentioned by Jeffreys 

 in P. Z. S., 1882, p. 663. Type is no. 107703 U. S. Nat. Mus., 

 formerly in Jeffreys' collection. C. dichelus is a stouter species. 



C. DICHELUS (Watson). PI. 26, fig. 73. 



Shell long, slightly swollen at about three-fifths of its length ; the 

 swelling bulges on the concave curve, but the convex curve is un- 

 interrupted ; between these two curves it is compressed by one-sixth 

 of its breadth, a little contracted in front, bent and attenuated to- 

 ward the apex ; thin, brilliant, white, almost hyaline, with a few 

 minute, transverse, curdy streaks, but weathering to opaque. There 

 is an opaque band round the apex. Sculpture : most faint and 

 delicate microscopic scratches on the lines of growth, with a minute 

 transverse flocculence and some vague indication of longitudinal 

 texture in the substance of shell. The mouth is large, very oblique, 

 with a smoothly rounded edge, which is sharp on the inner margin ; 

 both it and the posterior opening are oval. The apex, which is 

 small, is split on either side by a deep, narrow, slightly widening, 

 smooth, clean-cut, but not perfectly regular cleft, which is evidently 

 carried down the shell as the growth of the animal demands, for it 

 cuts across the transverse striae, as Mr. Searles Wood remarks is the 

 case with Siphodentalium (Dischides) bifissum. Within the opening 

 a short, minute, longitudinal, rib-like process projects along the 

 10 



