56 the proceedings of the linnean society 



4. — Dentalium sp ? 



Hab. Darnley Island, Torres Straits, 25 fathoms, sandy mud. 

 The greater part of this species is broken at the aperture. 



5. — Dentalium duodecimcostatum n. sp. 



Shell straight, white, thin, shining, smooth, six sided, having 

 two longitudinal rounded ribs, one on the edge of each square, 

 from the centre between the interstices one fine rib, extending to 

 the base, making in all 12 ribs ; apex tapering, entire with 

 minute perforation ; aperture large. 



Length, 11 lines ; diam. of apex, J ; base, 1 line. 



Hab. Darnley Island, Torres Straits, 30 fathoms, sandy mud. 



Only one specimen found. It differs from anything at present 

 known. The shell is six-sided, the base with twelve ribs, and 

 from the centre to the apex six, with the interstices smooth. 



6. — Dentalium roeustdm, n. sp. 



Shell nearly straight, thick, dull white, longitudinally 9 ribbed, 

 ribs rounded, wide apart, narrow towards the apex, interstices 

 flattened, smooth ; apex with small perforation, entire ; aperture 

 thickened, regular. 



Lengt i, 10 lines ; diam. of apex, § ; base, 1^ line. 



Hab. Katow, New Guinea, 8 fathoms, sandy mud and coral. 



7. — Dentalium katowense, n. sp. 



Shell white, thin, transparent, slightly arched near the apex, 7- 

 ribbed, from the centre to the base 14, those above being most 

 conspicuous ; interstices with minute lengthened stria? ; apex 

 thickened ; perforation small ; entire aperture circular. 



Length, 7 lines; diam. of apex, \\ base, 1 line. 



Hab. Katow, New Guinea, 8 fathoms, sandy mud and coral. 

 A white species with fourteen ribs on the base, having seven at 

 the apex more defined. 



8. — Dentalium pseudo-sexagonum. 



Dentalium pseudo-sexagonum, Desh. Sowerby, Thes. Conch., 

 vol. 3, p. 103, pi. 224, fig. 34. 



