15 



Diagnosis. Shell cylindrical, subulate, somewhat curved, grayish-white, somewhat trans- 

 parent. At the apex there are 6 strongly projecting equidistant angles ; between each of these 

 ribs a great many striae arise, covering the shell, and the primary ribs rapidly decrease and 

 disappear at the first fourth or third of the shell's length. Growth striae quite fine and often 

 regular. Length 45 — 50, greatest diameter 4 mill. (P. & Sh. from Desh.). 



Distribution. Masbate, Philippines; W.Columbia (Sowb.); Cape York, near Albany I. 

 North Australia, 11 fms; Darnley I., Torres Straits, 30 fms (Chevert Exp.) (P. & Sh.). 



This species is six-ribbed near the apex, finely striated below, as Mr Sowkrby expresses 

 it. The specimens before me have very fine threadlike ribs ; the number of ribs in all are from 

 24 to 25, and at or near the apex 6. Shell thin, white, slightly arched (Brazier). 



Mssrs PiLSBRY and Sharp think it very probable that "W. Columbia", cited by Sowerby 

 as a locality for this species refers to specimens of D. oerstedii Morch from the Panamic Province. 



No specimens were obtained by the Siboga Expedition. 



'''10. Dciitaliuin diiodeciincostatitin Brazier. 



1877. Dentaliiim duodeciincostatum Brazier, Proc. Lin. Soc. N. S. Wales II, p. 56. 



1897. DentaliHiii duodeciincostatuin Brazier. PiLSBRY & Sharp, Man. of Conch., vol. XVII, p. 13. 



Diagnosis. Shell straight, white, thin, shining, smooth, six-sided, having two longitudinal 

 rounded ribs, one on the edge of each square, from the center between the interstices one fine 

 rib extending to the base, making in all 12 ribs; apex tapering, entire with minute perforation; 

 aperture large. Length 22 mill., diam. of apex 0,5, base 2 mill. (Braz.). 



Distribution. Darnley Island, Torres Straits, 30 fms. sandy mud (Chevert Exp.). 



Remarks. Brazier adds: Only one specimen found. It difters from anything at present 

 known. The shell is six-sided, the base with twelve ribs, and from the center to the apex six, 

 with the interstices smooth. 



*ii. Dentaliiim porcatiiin Gould. PI. I, fig. 15. 



1859. Dentaliuin porcatnui Gould, Proc. Best. Soc. N. H. VII, p. \66. 



? Dentaliiim porcatuui Gould, Otia Conch. 

 1872. Dentaliiim porcatum Gould. SOWERBV, Conch. XVIII, pi. 7, fig. 47. 

 1897. Dentaliiim porcatum Gould. PiLSBRY & Sharp, Man. of Conch., vol. XVII, p. 15, 

 pi. 6, fig. 80. 



Diagnosis. Shell moderately curved, white, more or less ruddy at the ape.x six-ribbed 

 at apex, secondary riblets appearing first on the convex side, afterwards on the concave side, 

 increasing to 20 at the anterior aperture. Inter.stices micro.scopically longitudinally striated. Ape.x 

 with a short supplemental tube. Length 20, diam. 2,5 mill. 



Distribution. Hongkong Harbor, China (N. P. Expl. Exp.) Karachi (jVIelv. & St.). 



