388 HYDATINA. 



branch. It inhabits the Indo-Pacific region, from Africa to Japan, 

 Sandwich Is., and southeastern Australia, and reappears in the 

 West Indies. I am unable to find any constant differences between 

 oriental and occidental specimens. 



The typical physis is quite globose. The following has been sep- 

 arated as a variety. 



Var. STAMINEA Menke. PI. 45, fig. 14. 



Shell slenderer, oval, having oblique brown streaks. Occurs 

 in both Indian Ocean and West Indies. 



H. VELUM Gmelin. PI. 44, figs. 7, 8, 9, 10. 



Shell large, globose, thin ; spire flat or sunken, the sutures deep ; 

 under a very thin pellucid epidermis the surface is whitish, streaked 

 closely and longitudinally with light brown ; middle with a narrow 

 light girdle, bordered above and below with dark brown girdles ; 

 vertex with similar dark girdle, within which it is whiter ; base de- 

 fined by a fourth dark girdle ; surface smooth ; aperture ovate, 

 narrowed and curved above, dilated below, well-rounded at base. 

 Columella concave, reflexed over an open umbilical chink or closed. 

 Alt. 40, diam. 35 mill. 



Mauritius and Mozambique to Ceylon and East Indies. 



Vexillum nigritarum, etc., CHEMN., Conch. Cab. x, pi. 146, f. 

 1348, 1349. Bulla vexillum Chemn., A. AD., in Thes. Conch, ii, p. 

 565, pi. 12. f. 12-14 ; Voy. Samarang Moll. pi. 19, f. 4 (animal). 

 Hydatina vexillum SOWB., Conch. Icon. f. 4. Sulla velum GMELIN, 

 Syst. Nat. (13), p. 3433. Hydatina velum MKE., Mai. Bl. i, p. 41. 

 DESK., An. s. Vert, vii, p. 670. MARTENS, in Mobius' Reise, p. 

 304 ; Monatsber. K. Akad. Wissensch. Berl. 1879, p. 738. Bulla 

 cireulata MARTYN, Univ. Conch, pi. 95 ; Chenu's reprint pi. 32, f. 

 3. Bulla cinctoria PERRY, Conchology pi. 40, fig. 1. B. fasciata 

 BRUG., Ecycl. Meth. i, p.380. EYD. & SOUL., Voy. de la Bonite, p. 

 462, pi. 25 (animal and anatomy). B. amplustra BORN, Mus. Cses. 

 Vindob. p. 204, pi. 9, f. 1, not of Linne. 



The color-pattern is a well marked and constant character of this 

 species. 



H. ALBOCINCTA Hoeven. PI. 45, figs. 29, 30. 



Shell large, thin, spire slightly concave ; inflated, globose or oval; 

 under a very thin pellucid epidermis it is closely and finely ob- 

 liquely streaked with brown, interrupted by five wide, sharply 



