58 the proceedings of the linnean society 



12. — Dentalium quadricostatum, n. sp. 



Shell white, very slightly arched, four angled, keel or rib at 

 each angle, rounded, finely serrated, interstices flat, marked with 

 transverse lines ; apex perforated, perforation entire ; aperture 

 angled. 



Length, 8 lines ; diam. of base, 1 line. 



Hab. Princess Charlotte Bay, North-east Australia, 13 fathoms; 

 York Island, Torres Straits, 13 fathoms, hard mud bottom, 

 (brought up on the ship's anchor) ; Katow, New Guinea, 8 

 fathoms, sandy mud bottom. 



If this species is laid upon its side it forms a true square ; when 

 resting with the arched part of the apex down, it forms four 

 angles, with a serrated rib on each angle. The 11 specimens 

 from Katow, 16 from Princess Charlotte Bay, and 1 from York 

 Island, all have the same character. 



13. — Dentalium dispar. 



Dentalium dispar, Sowerby, Thes. Conch., vol. 3, p. 103, pi. 

 244, fig. 37. 



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

 One specimen, nine lines long, was found, a glossy and smooth 

 shell below, with fine ribs at or near the apex. 



14. — Dentalium anulosum, n. sp. 



Shell thin, transparent, tapering, slightly curved, marked by 

 incised circular lines from the apex to the centre, and from that 

 to the base quite smooth, apex thickened, perforated, perforation 

 entire, aperture circular. 



Length, 7 lines. 



Hab. Princess Charlotte Bay, North-East Australia, 13 fathoms, 

 sandy bottom. 



The upper part of this beautiful thin, transparent shell has a 

 ringed appearance like a trachea. Allied to Dentalium politum, 

 Linn., that species being distinguished by the incised lines that, 

 divide its whole length. 



