DENTALIUM-ANTALIS. 51 



Key to species. 



I. 9 to 13 strong ribs at and near apex ; an equal number of inter- 

 stitial ribs often developed, or intervals longitudinally striated. 

 a. Primary ribs strong, intercalated riblets generally smaller 

 througbout, sbell generally ruddy, vovemcostaium, dentalis, 

 incequicostatiim, panormum. 

 a'. About 11 indistinct ribs, intervals longitudinally striated, 

 apex wide ; white; (Gulf of Suez), davus,\i. 55. 



II. 12 or more low ribs at apex, increasing to double that, and be- 

 coming lower or obsolete toward aperture, occidentale, p. 47. 

 III. 11-28 primary ribs or riblets, continuous from end to end; no 

 interstitial riblets or longitudinal striae ; white. 

 a. 11-13 ribs; length 35 mill., 7 times the diam. 



senegalense, p. 55. 



a'. 26-28 narrow ribs; no apical notch; length 25 mill., 12 



times the diam., cenigmaticwn, p. 49. 



D. NOVEMcosTATUM Lamarck. PI. 9. figs. 44, 45, 46, 47, 48. 



Shell moderately curved, very stout; grayish-white or delicate 

 rose, usually reddish toward the apex and with encircling zones of 

 deeper red. Sculpture of 9 rounded ribs, stronger at the apex, weak 

 or obsolete at the aperture; longitudinally obeoletely striated. 

 Aperture rounded-angular. Apex wide, truncate, the anal orifice 

 small, usually occupying a short tube. 



Length 32, diam. of aperture 4"7, of apex 2-3 mill. 



Ocean coast of France. 



D. novemcostatum Lam., An. s. Vert., v, p. 344 (1818); edit. 

 Desh., V, p. 592 (1838).— Desh., Mem. Soc. Hist. Nat. Paris, ii, p. 

 356, pi. 16, f. 11, 12 (1826).— Delessert, Req. de Coq., pi. 1, f. 2a, 

 2b (1841). — Fischer, Actes Soc. Linn. Bord., xxvii, 1869, p. 115. 

 — Daniel, Journ. de Conchyl., xxxi, 1883, p. 331. — Buq., Dautz. 

 & DoLLF., Moll, du Roussillon, i, p. 565, pi. 66, f. 12-1-^. — Sowb., 

 Thes. Conch., iii, p. 102, pi. 224, f. 24-27 ; Conch. Icon., xvii, pi. 3, 

 f. 136, c, d. — Clessin, Conchyl. Cab., p. 5, pi. 1, f. 5. — Antale novem- 

 costatum Sacco, Boll. Mus. Zool. ed Anat. Comp. Univ. Torino, xi, 

 1896, p. 97. 



Stouter, comparatively broader in the adult than the Mediterranean 

 D. incequicostatum, and lacking the distinct circular striation of that 

 form. 



