38 GEN A. 



Subgenus GENA s. str. 



G. PLANULATA Lamarck. PI. 55, figs. 1, 2, 3 ; pi. 2, figs. 17-20. 



Shell much flattened, oval, the spire very minute, and very near 

 the end; aperture almost as long as shell, its margins level, not 

 arched. 



Oval-oblong in contour, the two sides about equally curved ; much 

 flattened, like a Navicella. Surface shining, very densely and 

 minutely striate in the direction of the whorls. Color, very deep 

 blackish-olive with white dots, or finely variegated and marbled all 

 over with gray and olive-brown ; under a lens seen to be finely 

 articulated on the stride. Whorls 3, spire minute, not projecting 

 beyond the general outline of shell. Aperture very large, oval, the 

 columellar and lip margins equally curved, upper end rounded, 

 a pearly callus filling the angle ; interior nacreous, with blue-green 

 and fiery-red reflections. Length 19, breadth 10 mill. ; aperture, 

 length 16J, breadth 9 mill. Length 17, breadth 10 mill. ; aperture, 

 length 15, breadth 9 mill. 



Philippines ; Australia. 



Stomatella planulata LAMARCK, Anim. s. Vert., ed. Desh. ix, p. 

 17. En eye. Meth., t. 458, f. 4. Gena planulata Lam., AD. in Thes. 

 Conch, ii, p. 829, t. 173, f. 1-3. 



This species is more depressed and flattened than any other. The 

 spire is very minute. The aperture is not angulated posteriorly, but 

 rounded by a callus which fills the angle. 



G. NIGRA Quoy & Gaimard. PI. 51, figs. 20, 21. 



Shell elongate-oval, convex, smooth, black ; right margin longitu- 

 dinally striate, violaceous shining within ; spire minute, subter- 

 minal ; aperture oval, entire. 



A very elongated little species, contracted, convex, arched so as to 

 rest upon the extremities alone; the spire is short, nearly terminal 

 on the right margin, composed of 4 whorls. The right margin has 

 six or seven longitudinal striae, the others, parabolic behind and in 

 front, are incremental. This shell is shining black above, with viola- 

 ceous nacre within the entire oval aperture. (Q. & G.) 



Tonga- Taboo. 



Stomatella nigra Q. & G., Voy. de PAstrolabe, Zool. iii, p. 307, t. 

 66, f. 10-12, 1834. 



