128 DENTALIUM-FUSTIARIA. 



D. POLITUM Linne. PL 19, figs. 18, 19, 20, 21. 



Shell slender, long, slowly tapering and regularly arcuate, polished. 

 Sculptured with many narrow encircling grooves, parallel with the 

 peristome, and dividing the surface into narrow, oblique segments. 

 Aperture somewhat oblique, circular, the peristome acute. Anal 

 orifice rounded-ovate, somewhat channelled within at the position of 

 the slit. Slit an extremely narrow and long cleft on the convex 

 side. 



Length 58, diam. aperture 49 mill. 



Length 39, diam. aperture 3*3 mill. 



Paris Basin Eocene at Grignon, etc. ; recent in Indian Seas (Desh., 

 Hanley). 



Dentaliiim politwn Linne, Syst. Nat. (12), p. 1264 (1766).— Han- 

 ley, Ipsa Linn. Conch., p. 438 (1855) ; Sowerby, Thes, Conch., iii, 

 p. 99, pi. 225, f. 46 ; Conch. Icon., pi. 6, f. 38 (1872).— Z). ehurneum 

 SowB., Genera of Shells, Deutalimn, f. 6. — Desh., Mem. Soc. Hist. 

 Nat. Paris, ii, p. 368, pi. 17, f. 8, 9 (1825) ; An. s. Vert. Bassin 

 Paris, ii, p. 215, pi. 2, f. 11-13 (1864). Not D. ehurneum l^.—D. 

 subeburneum Orb., Prodr. de Paleont., ii, p. 372 (1850). 



This species is closely allied to D. circinatum Sowb., but is less 

 slender. The two were formerly united by Deshayes, and Newton 

 (Brit. Oligocene and Eocene Moll., 1891) still includes both under 

 circinata. Whether the Eocene and living specimens referred to Z>. 

 politum are identical is a question we have no means of answering, 

 as we have seen no recent specimens. It is admitted to the modern 

 fauna on the authority of Deshayes and Sowerby who state that they 

 have examined oriental recent shells, although the former in his Paris 

 Basin Invertebrates (p. 216) thinks that Linnseus' shell may have 

 been a fossil one. 



D. STENOSCHizuM Pilsbry & Sharp, n. sp. Pi. 19, figs. 10, 11, 12, 

 13, 14, 15. 



Shell rather strongly arcuate toward the smaller end, rapidly 

 tapering, the- earlier portion slender and delicate, the length about 10 

 times the diameter of aperture. Milk-white, somewhat translucent. 

 Very glossy and polished throughout, and entirely tvithout sculpture 

 except for slight, inconspicuous annuhir irregularities of growth. 

 Aperture slightly oblique, nearly circular, being a trifle compressed 

 laterally ; peristome thin. Anal orifice circular, with thin edges. 

 Slit extremely narrow, linear, and long, its length contained about 

 3i times in length of shell, situated on the convex side. 



