DENTALIUM. 3 



GROUP OF D. APRINUM. 



Shell slender and long, well curved, green, with few or many 

 longitudinal ribs. No apical slit. 



Key to species. 



I. 9 to 12 conspicuous, narrow ribs from apex to aperture. 



a. Interstitial sculpture weak aprinwn, p. 3. 



a'. Small interstitial riblets interstriatum, p. 4. 



II. 8 ribs, intervals wide and flat javanum, p. 4. 



III. Numerous riblets, 17 at apex, about 25 at aperture 



letsonce, p. 4. 



D. APRINUM Linne. PL 1, figs. 8, 12, 14. 



Shell long, slender and well curved, the diameter about one- 

 twelfth the length ; solid, glossy, pale green, usually somewhat 

 lighter toward the anal end. Sculpture, 9-12 conspicuous but 

 narrow rounded longitudinal ribs, separated by much wider, flat, 

 polished intervals, often parted by a faint median riblet, and usually 

 showing numerous very slight longitudinal striae; the ribs stronger 

 on the concave side ; growth strise inconspicuous. Aperture circu- 

 lar ; anal orifice very small and circular, its edge crenated by the 

 ribs ; no slit. Length 70, greatest diameter 6 mill. 



Zebu, Philippine Is. (Cuming). 



D. aprinum LINN., Syst. Nat. (12), p. 1263 (1766). HANLEY, 

 The Shells of Linn., p. 436. GMEL., Ibid (13), p. 3736. LAM., 

 An. s. Vert., v, p. 343 (1818). DESK., Mem. Soc. Hist. Nat. Paris, 

 vii, p. 351, pi. 16, f. 18 (1825). SOWB., Thes. Conch., iii, p. 102, 

 pi. 223, f. 5, 6 ; and in Conch. Icon., xviii, pi. 1, f. 2 a, b. CHENU, 

 lllustr. Conchy 1., p. 2, pi. 1, f. 11, 12. D. caprinum ANTON, Ver- 

 zeich., p. 25, (1839). D. striatulum GMEL., Syst. Nat. (13), p. 3738 

 (1788). WOOD, Index, p. 84, No. 4. D. striatum (in part), BORN, 

 Test. Mus. Cses. Vindob.,p. 431. 



Not D. aprinum Risso, Hist. Nat. Eur. Merid., iv, p. 399 (1826). 

 BROCCHI, Conch. Foss. Subappen., ii, p. 264 (1814). COSTA, 

 Fauna Reg. Nap., p. 34 (1850), or of other authors on Italian mol- 

 lusks. 



The Japanese multangular tusk shells are nearly allied, but are 

 white, while aprinum is pea green in color. 



