108 DENTALIUM-L^VIDENTALIUM. 



toward the middle, brilliantly polished. Sculpture none, except 

 for occasional circular grooves indicating growth periods, Aper- 

 ture subcircular, a little compressed between the convex and con- 

 cave sides, not oblique. Anal orifice circular, with a narrowly v- 

 shaped notch on the convex side (fig. 38). Length 25-3, greatest 

 diameter 2, diam. of apex 0'6 mill. 



St. Martin, Wet Indies (E. Marie). 



The general appearance of the shell -is like D. semistriaium 

 Turton, but longitudinal striae are wanting, and it is evidently 

 allied to D. translucidum and other similar species here grouped. 

 It differs from translucidum, ambiguum, subtorquatum and lacteum 

 in having a well developed slit, among other less conspicuous feat- 

 ures. 



Var. ? alloschismum P. & S. PL 21, figs. 40, 41, 42. 



Like the preceding, but the slit is on the concave side, either sub- 

 median (fig. 40) or to the side (fig. 41). 



Length 24*5, diam. at aperture 1/9, at apex 0*6 mill. 



Length 27'5, diam. at aperture 2'2, at apex 0'6 mill. 



St. Martin (figs. 40, 40) ; West Indies, without nearer location 

 (figs. 41, 42). 



In view of the considerable variation observed in the position, 

 shape and even presence or absence of the slit in other species, we 

 hesitate to give this form rank higher than varietal The section 

 of the tube is circular in the variety, a little flattened in the type, 

 but other characters seem identical. The specimen represented in 

 figs. 41, 42 seems to be somewhat worn at the apex at the termina- 

 tion of the slit. The latter is decidedly excentric, fig. 41 being 

 viewed directly upon the concave side. 



D. BISINUATUM Andre. PL 19, figs. 7, 8. 



Shell conic, perfectly circular in transverse section, little curved, 

 thin, translucid, glossy, of a yellowish corneous color ; with oblique, 

 regular, fine transverse striae. Aperture circular, a little oblique ; 

 peristome sharp, irregular. Apex with two small notches, one ven- 

 tral, the other dorsal, a little deeper than the former. Length 33'5, 

 diameter of the aperture 3, of apex 0'5 mill. {Andre). 



Amboyna. 



D. bisinuatum ANDRE, Revue Suisse de Zool. et Ann. du Mus. 

 d'Hist. Nat. de Geneve, iv, fasc. 2, p. 397, pi. 17, f. 9 (Dec., 1896). 



This species is allied to D. splendidum Sow. ; the size of the lat- 

 ter is greater, and the notches of the apex are continued in a slit 



