90 DENTALIUM-GRAPTACME. 



a deep narrow dorsal notch. Color delicate salmon or yellow, 

 gradually shading into white toward the anterior end. Length 

 31*5 mill., anterior diam. 2, posterior diam. about 0'5 mill. (BusJi). 



Vicinity of Cape Hatteras, N. C., to Charlotte Harbor, Florida in 

 2-50 fms. ; older Miocene of Chipola River, Florida. 



D. leptum BUSH, Trans. Conn. Acad., vi, p. 470, pi. 45, f. 18 t 

 18a (1885) ; Rep. U. S. Fish Commission for 1883, p. 586 (1885). 

 -DALL, Blake Rep., Bull. M. C. Z., xviii, p. 421 ; Bull. U. S. 

 Nat. Mus., No. 37, p. 76 ; Trans. Wagner Inst., iii, p. 440 (1892). 



This beautiful and distinct species is readily recognized by its 

 orange tint and slender form, delicately and closely striated near 

 the tip. (Dall). 



Some of the Fish Commission specimens marked leptum from off 

 Hatteras proved to be D. matara. 



D. SEMISTRIATUM Turton. PI. 16, figs. 51, 52, 53. 



Shell slender, tapering and attenuated posteriorly, translucent- 

 white, milky, sometimes slightly tinted toward the apex, polished. 

 Sculpture of fine, regular, clearly cut and close longitudinal grooves 

 separating narrow lirulce, which extend over the posterior third (more 

 or less) of the shell's length ; the remainder very glossy, without sculp- 

 ture other than slight irregularities of growth. Aperture somewhat 

 oblique, circular. Anal orifice minute, circular, and normally un- 

 slit. 



Length 26, diam. of aperture 2'2-2'6, of apex 0'6 mill. 



Carribean Is. : St. Martins (E. Marie), and Saba (Swift). 



D. semistriatum TURTON, Conchol. Diet. Brit. Is., p. 39, pi. 18, f. 

 68 (1819) ; compare Forbes and Hanley, Hist. Brit. Moll., ii, p. 454. 

 D. translucidum CHENU, 111. Conch., i, p. 8, pi. 3, f. 12, not of 

 Deshayes. D. semistriolatum GUILDING, Trans. Linn. Soc. Lond., 

 x vii, pt. 1, p. 34, pi. 3, f. 1-5 (1834). 



Both Turton and Guilding have given good descriptions and fig- 

 ures of this species, although later writers have singularly overlooked 

 them. We believe the West American form, D. semipolitum B. & 

 S., with its synonyms, to be identical, numerous specimens before us 

 showing no constant differential characters. The species differs 

 from D.sericatum Dall in lacking the conspicuous (though variable) 

 zig-zag color-pattern, and the tube does not increase so rapidly. D. 

 leptum Bush is more slender, the length fully 15 times the diameter 

 of aperture ; D. eboreum is also more attenuated and straighter. 



