82 DENTALIUM-FISSIDENTALIUM. 



rather acute ribs at the apex, becoming rounded anteriorly, and 

 either splitting to form about three minor riblets, or not noticeably 

 divided but having several strong longitudinal cords developing in 

 each interval ; all longitudinal sculpture subobsolete near the aper- 

 ture, where growth-strise predominate in old individuals. Aperture 

 circular, quite oblique. Anal orifice with a slight sheath (as in en- 

 tails) and a long, usually crooked slit. 



Length 111, aperture 14 x 14 mill., slit 12 mill, long (old speci- 

 men). 



Length 99, aperture 13 x 13 mill., slit 19 mill, long (hardly ma- 

 ture). 



Living, in Eastern Atlantic (Travailleur Exped.) ; Pliocene of 

 Monte Pellegrino, Sicily, Rhodes, etc. 



D. delessertianum Chenu, Illustr. Conch,, i, Dentalium, p. 3, pi. 6, 

 f. 10. — Fischer, Journ. de Conchyl., 1882, p. 276. — D. delesserti 

 Chenu, Manuel de Conch., i, p. 374 (1859) ; also Dentale de Deles- 

 sert, Lecons Elem. d'Hist. Nat, p. 141, f. 448 (1847).— Cf. also 

 FoRESTi, Bull. Soc. Mai. Itid., xix, pp. 240, 242. — D. elephantinum 

 and D. rectum of many writers on Pliocene fossils of the south of 

 Europe. 



Our diagnosis is from Monte Pellegrino Pliocene specimens. 

 Chenu's description is as follows : 



Shell ver}" large, multicostate, with several small riblets between 

 the ribs. This fossil species is the largest and one of the finest of 

 the genus. It has 10 or 12 large and raised ribs, with 3 or 4 

 smaller riblets in the intervals; smaller end obliquely truncate and 

 well slit (Chenu). Length 114, greatest diam. 13 mill, (from fig.). 



The aperture is more oblique than in D. rectum. The identity of 

 this species with D. philippii Monts. affirmed by DeFranchis and 

 Foresti is somewhat doubtful, but we have not material enabling 

 us to attempt a rectification of the nomenclature of Italian Pliocene 

 and Postpliocene species. The synonymic knots are worse than 

 Gordian, and there are several tied to each species. 



D. PLURiFissuRATCM (Sowerby). PL 6, figs. 87, 88, 89. 



Shell subulate, rather thick, slightly curved posteriorly and at- 

 tenuated ; pale; longitudinally very delicately striated and having 

 many unequal riblets; irregularly roughened circularly. Fissures 

 2 to 5, the first (near the apex) generally long, the rest shorter. 

 Length 64, greatest diam. 7'5 mill. (Soicb.). 



Hong Kong f 



