116 DENTALIUM-RHABDUS. 



Length 59, antero-posterior diam. apert. 4*7, lateral diara. 4'5 ; 

 diam. apex 0'9 mill. 



Length 66, diameters of aperture 53, of apex 0*9 mill. 



Singapore (Dr. S. Archer) ; Sullivan Island, Mergui Archipelago, 

 in 7 fms. (Anderson) ; Also Siam and Philippine Is. (authors). 



D. eburneum LINN., Syst. Nat. (12), p. 1264 (1767). GMELIN, 

 p. 3737. LAM., An. s. Vert., v, p. 346 (1818). HANLEY, Ipsa 

 Linnei Conchylia, p. 438 (1855). SOWB., Thes. Conch., iii, p. 98, 

 pi. 225, f. 53 (I860) ; and in Conch. Icon., xviii, pi. 3, f. 16 (1872). 

 MARTENS, Journ. Linn. Soc. Lond., Zool., xxi, p. 200. Not D. 

 eburneum Desh., I825,=politum Linn. D. politum MAWE, The 

 Linn. Syst. Conch., p. 191, pi. 33, f. 6 (1823). CROUCH, Illustr. 

 Introd. Lam. Conch., p. 1, pi. 1, f . 2 (1827).? DESH., Mem. Soc. 

 H. N., Paris, ii, p. 361, pi. 16, f. 17 (1825), and in Lam., An. s. Vert, 

 edit. 2, v, p. 597. Not D. politum Linne. D. indicum CHENU, 

 Illustr. Conchyl., i, Dentalium, p. 4, pi. 3, f. 11. D. annulare G. B. 

 SOWERBY, Zool. Journ., iv, p. 199 (1828). 



D. eburneum of nineteenth century authors before 1855 is D. poli- 

 tum Linn, as Hanley has shown. The species is remarkable for its 

 irregularly placed, low, swollen rings. All of the specimens before 

 me with definite and reliable locality data, are from Singapore. 



D. PHILIPPINARUM Sowerby. PI. 20, figs. 31, 32. 



Shell similiar to D. eburneum, but less curved, less tapering, the 

 posterior end being larger and the aperture smaller than in spec- 

 imens of eburneum of the same length ; polished, with low, irregular 

 variceal rings and some circular impressed lines, and showing dis- 

 tinct traces of longitudinal striation in some places. Translucent 

 whitish. 



Length 56, diam. of the subcircular aperture 3*7, of the apex 1*3 



mill. 



Island of Samar, Philippines (Cuming). 



D.philippinarum SOWB., Thes. Conch., iii, p. 98, pi. 225, f. 54 

 (1860) ; and in Conch. Icon., pi. 3, f. 18 (1872). 



This tusk-shell is evidently very closely allied to D. eburneum, but 

 our material does not permit us to unite the two, although it is not 

 improbable that intermediate specimens will be found. Sowerby 

 thus describes it: 



Shell elongated, very narrow, rather straight, semipellucid, highly 

 polished, somewhat golden brown, banded with numerous elevated 



