NO. 2183. NEW NORTHWEST AMERICAN BIVALVES— BALL. 407 



white. Length, 27; height, 18.5; diameter, 14.6 mm. Cat. No. 

 122564, U.S.N.M. 



Station 3074, off Sea Lion Rock, coast of Washington, in 877 

 fathoms. 



CETOCONCHA MALESPINAE, new apedes. 



Shell small, very thin, with prominent prosocoelous beaks, a very 

 pale yoUowish olive periostracum, darker on the posterior dorsal area; 

 in the right valve is a strong radial ridge near the posterior hinge line; 

 surface otherwise smooth and almost pohshed except for extremely 

 fine radial lines of minute granules only visible under a glass; shell 

 very similar to Isocardia cor in form and outUne on a very small scale; 

 interior white, the hinge normal but weak. Length. 12.5; height, 10; 

 diameter, 8.5 mm. Cat. No. 212564, U.S.N.M. 



Station 2859, southwest of Sitka Bay, Alaska, in 1,569 fathoms. 



MYONERA TILLAMOOKENSIS, new species. 



Shell extremely thm, fragile, inflated, beaks nearly central (neglect- 

 ing the rostrum), whitish, the anterior part of the shell with about 20 

 strong, rounded, concentric ripples which cease posteriorly at the 

 anterior border of the radial sculpture which includes four strong and 

 about fifteen threadlike radial riblets extending from the beaks to the 

 base, behind which is a short, blunt, concentrically feebly striate, 

 truncate rostrum; base arcuate, hinge-line nearly straight, the right 

 margin slightly overlapping the other. Length, 18; height, 12; 

 diameter, 10 mm. Cat. No. 107819, U.S.N.M. 



Station 3346, off Tillamook Bay, Oregon, in 786 fathoms. 



CUSProARIA APODEMA, new species. 



Shell small, white, polished, swollen, with a prominent tubular 

 rostrum; inequilateral, the beaks 6 mm. behind the anterior end; 

 the rostrum about 5 mm. long; beaks conspicuous, prosocoelous; 

 the exterior smooth except for incremental lines and wrinkles on the 

 dorsal side of the rostrum; hinge-line nearly straight, anterior end 

 rounding imperceptibly into the semicircular base which is suddenly 

 constricted at the rostrum. Length, 17; height, 10; diameter, 8 mm. 

 Cat. No. 122602, U.S.N.M. 



Station 2859, southwest of Sitka Bay, Alaska, in 1,569 fathoms. 

 Near but not C. obesa LovSn, of the Atlantic. 



CARDIOMYA BALBOAE. new species. 



Shell small, whitish with a yellowish periostracum; inequilateral, 

 rostrate, somewhat inflated, posterior end shorter, anterior ovately 

 rounded; beaks small, pointed, not elevated; sculpture of anterior 

 half of the disk faintly irregularly concentrically rippled; behind 

 this 12 to 15 radial, more or less alternated threads extending to the 



