Dr. H. Woodward — On Fossil Shells from Sumatra. 537 



Although the divergence pointed out between our Sumatran 

 shell and the recent Pleurotoma sinensis of Hinds may be deemed 

 sufficient in the eyes of recent students of Malacology to separate the 

 two specifically, yet we venture to think it probable that we have in 

 PL sinensis, Hinds, only the modern representative of the Sumatran 

 fossil, and also of the PI. terebra, Bast., with its associated forms 

 from the Miocene of France. 



Should this view find favour, then four species, hitherto separated, 

 will in the future be enrolled under one name, as PI. terebra, Bast., 

 or be treated as varieties only, a method particularly convenient 

 in dealing with genera of Mollusca, which are extremely rich in 

 species and varieties, like Pleurotoma. 



Formation : — In bluish-grey Tertiary Maid-clay. 



locality : — Government of the West Coast of Sumatra. 



52. Pleurotoma concinna, Dunker, 1856. PL XIV. Fig. 3a, b. 

 Proc. Zool. Soc. Lond. 1856, p. 356. 



The following is a translation of Prof. Wm. Dunker' s description 

 of Pleurotoma concinna : — 



Shell acutely-turrited, subfusiform, solid; colour light-reddish 

 brown; mouth and canal roseate, encircled with elevated lines and 

 ridges; whorls about 10, slightly convex; suture indistinctly divided; 

 last whorl scarcely equal to the height of the spire ; canal sub- 

 oblique ; fissure in outer lip deep. 



Dimensions of recent shell : length 27 mm. ; greatest breadth 9 mm. ; 

 length of aperture 12 mm. 



There can be no doubt of the identity of our fossil, PI. XIV. 

 Fig. 8, with the living Pleurotoma concinna, of Dunker, specimens 

 of which are preserved in the British Museum, said to have been 

 obtained from Sibonga in the Philippine Islands, and from New 

 Ireland. It differs from that species, at first sight, in being shorter 

 and of less slender build, with a shorter basal canal. (The length 

 of the canal, however, should in all probability have been greater 

 than the artist has represented in our Figure, as the extremity of the 

 canal is certainly abraded.) 



The whorls in the fossil are more deeply excavated than in the 

 recent specimens, both above and below the central carina, the 

 nodules of which are more clearly defined in the fossil. The other 

 spiral lirse and oblique sculpture also offer certain differences. The 

 suture is less deep in the fossil than in the recent shell from New 

 Ireland, but equals that of the type specimen. In the fossil form 

 the surface reticulations are more strongly marked than in the 

 recent species, approaching in this respect more nearly to the 

 PI. cataphracta of Brocchi from Dax. It agrees also with PL 

 Hantoniensis, Edw., in having the line of tubercles upon the central 

 carina divided into two ; but the striae in PL Hantoniensis are some- 

 what coarser and less markedly reticulated. This shell might also 

 be compared with Pleurotoma turbida, Solander, and PL granata, 

 Edw. Near the apex the four earliest whorls of the young shell in 

 the fossil are seen to be roundly inflated and simply ribbed longi- 



