268 BULLETIN OF THE 
series of the C. obesus, and find nothing closely resembling it, either among 
the specimens or in the literature. It is very much flatter and thinner than 
C. obesus; its texture is of a less earthy and solid character; the base is more 
produced in the middle and less evenly rounded. The flattish high and pointed 
beaks are also noteworthy. It is nearer C. obesus than to any other form, and 
consequently other comparisons are hardly needed. I had formed the idea 
that this genus was marked by great variability, but my study of the Jeffreys 
series has convinced me that it is much less so than I had supposed. The 
species do vary in breadth and in the sharpness of their flexures, but the 
identification of the species is not especially difficult. 
Famity CHAMID. 
Genus CHAMA Bruciire. 
Chama lactuca, n. s. 
Shell attached usually by the left valve ; valves differently sculptured ; free 
valve orbicular, moderately convex, tip not greatly enrolled ; sculptured with 
radiating and concentric series of very small short spines, each grooved under- 
neath, generally only the marginal series raised so as to appear spiny and these 
only slightly so, the rest look like little radiating nodulations of which the 
radii are discontinuous with each new period of growth; attached valve in- 
flated, smooth, polished, gyrate like a much enrolled Capulus, with indistinct 
lines of growth and a succession of flat, wide, very thin, sharp concentric 
lamella, separated by rather wide and gradually increasing interspaces ; the 
lamellz nearly complete the circuit of the valve, and are interrupted only near 
the dorsal margin, are slightly recurved, their margins usually irregular from 
small fractures ; their anterior or, rather, distal faces, are microscopically ra- 
diately shagreened, and just in front of each lamella is a narrow band with 
stronger and more distant radiations ; interior smooth, the cavity of the left 
valve extending to the tip of the enrolled beak ; the color is usually white, or 
marked with concentric rings of pale livid brown corresponding to periods 
of growth; margin smooth; muscular impressions narrow, marginal; hinge 
weak, of two lamellar teeth in each valve, the anterior the larger; ligament 
hidden in a deep groove so as to be practically internal ; longest diameter 
‘about 25.0, shorter about 15.0 mm. 
Habitat. Barbados, 80-100 fms., dredged by the “ Hassler.” 
The apical portion of the valve is shaped like Tellimya, polished and claret- 
colored. It may be well to call attention to the fact that the very young 
Chama (macrophylla) has a shell shaped like Cypricardia, with similar hinge 
teeth and a simple pallial line; the adults have very similar characters in the 
soft parts, except such as are more or less dependent on the habitus. There 
can be no doubt of the near relation of the two. 
