NO. IO MOLLUSKS BARTSCH AND REHDER 1 3 



desma?) picta Sowerby described from the Isla Muerte, Ecuador, but 

 the color markings of this species are black on a brown base. Whether 

 this species has the granular sculpture is not known. 



CHAMA RUBROPICTA, n. sp. 

 Plate 3, figs. 6-10 



Shell small, suborbicular, the left valve sessile and sharply angu- 

 late so that the anterior part is affixed to the substratum, and the 

 posterior part rises vertically from the base. The left valve is dis- 

 tantly lamellose and fimbriated where it is attached ; the rest of the 

 surface shows .irregular, discontinuous vertical ridges which are of an 

 orange-scarlet color on a ground which is of a very pale pinkish blush, 

 except near the base, where it is white ; there are also present scattered 

 lamellose spines. The right valve is slightly convex, closely fimbriately 

 lamellose, with occasional semitubular or lamellose spines, and of a 

 general scarlet color, except near the anterior dorsal edge, where it is 

 white. The interior of the right valve is vivid scarlet, except for a 

 white anterior portion ; the left valve is white inside with a narrow 

 pale orange-scarlet stripe running from the umbonal region to the 

 dorsal edge. The left valve has a rather short stout cardinal tooth 

 which is grooved on the dorsal edge ; the right valve has a somewhat 

 longer, narrower cardinal. The ligament is posterior to the umbones, 

 slender and curved. The margins of both valves are denticulate, and 

 the affixed portion of the left valve shows crowded low radial grooves 

 which terminate at the marginal crenulations. 



The type, U.S.N.M. no. 472553, measures: Height, 11 mm.; 

 length, 9.1 mm. It was collected on rocks to the south of the landing 

 place on Clipperton Island. 



CTENA CLIPPERTONENSIS, n. sp. 



Plate 3, figs. i-S 



Shell white, broadly transversely oval to subcircular, moderately 

 inflated, with the umbones prominent and anterior to the middle. The 

 anterior end is slightly flattened, the posterior end broadly rounded. 

 Lunule broadly ovate. The sculpture consists of a few, closely 

 spaced, rounded radial riblets, crossed by crowded concentric rounded 

 lamellae, which render the riblets nodulose ; the radial and concentric 

 sculpture is of equal strength and is only brought out clearly under 

 magnification. The interior is white with the muscle scars well de- 

 fined, the anterior one being suborbicular, the posterior one elongate 



