78 BULLETIN 111, UNITED STATES NATIONAL MUSEUM. 



(?)1870. Dentalium gracile Jeffreys, Ann. and Mag. Nat. Hist., ser. 4, vol. 6, 



p. 74. 

 (?)1880. Dentalium gracile Jeffreys, Ann. and Mag. Nat. Hist., ser. 5, vol. 6, 

 p. 317. 

 1889. Dentalium filum, Dall, Bull. Mus. Comp. Zool., vol. 18, p. 419. 

 1889. Dentalium filum, Dall, Bull. 37, U. S. Nat. Mus., p. 76. 

 1892. Dentalium filum, Dall, Trans. Wagner Free Inst., Phila., vol. 3, p. 44. 

 (?)1896. Dentalium filum, Clessin, Conchvlien Cab., vol. 6, pt. 5, p. 8, pi. 4, 



fig. 5. 

 (?)1896. Dentalium fistula, Clessin, Conchylien Cab., vol. 0, pt. 5, p. 22, pi. 6, 

 fig. 10. 

 1897. Dentalium soiverbyi, Pilsbry and Sharp, Tryon's Man. Conch., vol. 17, 

 p. 117, pi. 20, fig. 30. 

 (?)1897. Dentalium fi^stula, Pilsbry and Sharp, Tryon's Man. Conch., vol. 17, 

 p. 118, pi. 18, fig. 4. 

 1897. Dentalium filum, Pilsbry and Sharp, Tryon's Man. Conch., vol. 17, 



p. 118, pi. 18, fig. 9, in part. 

 1903. Dentalium filum, Dall, Bull. 37, U. S. Nat. Mus., p. 76 (not D. sowerbyi 

 Chenu, Conch., 111., p. 7, pi. 6, fig. 2) (not D. filum, Dall and Simp- 

 son, Bull. U. S. Fish Comm., for 1900, vol. 1, p. 456). 



The shell is very small and slender, of round section, thin, but 

 not fragile, moderately and regularly curved, slowly and regularly 

 increasing in diameter. In texture it is vitreous, either transparent, 

 or merely translucent on account of being clouded by more or less 

 opaque rings. Tiie color is white, occasionally tinged with salmon. 

 There is no trace of longitudinal sculpture. Many rings of growth 

 closely crowded together upon the transparent tips are often observ- 

 able under a lens. Slight irregularities of growth prevent the sur- 

 face from being perfectly smooth, and therefore less polished than 

 in many vitreous species, but a Cuban form is absolutely smooth 

 and glistening. The apex is generally squarely cut across and from 

 the orifice projects a very thin inner tube. There is no apical notch 

 or slit. Measurements are: 



Length, 13 mm.; diameter, 1.5 mm.; arc, 0.5 to 1. 



Hatteras region, in 17 to 124 fathoms; Florida Keys region, 8 to 

 180 fathoms; Gulf of Mexico, 60 to 85 fathoms; Cuba, Barbados. 

 It is probably widely distributed throughout the entire Antillean 

 region in shallow to moderate depths. 



Known in American collections as ''DentaliuTn filum Sowerby," 

 the name chosen by Doctor Dall in the Blake report for various 

 lots from the Hatteras region. Sowerby's D. filum and D. fistula 

 and Jeffrey's D. gracile were all described from east Atlantic locali- 

 ties, and their identity with our species is very questionable. Guild- 

 ing's D. sowerbyi antidates all others, and was, moreover, described 

 from the Caribbean. Although inadequately described, there can 

 be no doubt it is the species under consideration. 



