268 BULLETIN OF THE 



series of the C. obesv^, and find nothing closely resembling it, either among 

 the specimens or in the literature. It is very much flutter 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 ray 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. 



Family CHAMID^. 



Genus CHAMA BRUGitRB. 



Chama lactuca, n.. s. 



Shell attached usually by the left valve ; valves diff'erently 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 noduhitions 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 

 lamellce, separated by rather wide and gradually increasing interspaces ; the 

 Lamellae 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 

 Clxama (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. 



