190 NEW WEST AMERICAN SHELLS — BALL. 



posterior lateral. The teeth become more or less obsolete in old shells. 

 The mantle edge is miuutely fringed, the siphonal openings papillose, 

 the foot stout, blunt, ovate cylindrical. The shell is earthy in texture. 



Calyptogena pacifica, sp. nov. 



Shell equi valve, elongate, ovate, white with a thick greenish epidermis ; 

 sculpture of incremental lines ; form much like Petricola carditoides 

 Conrad, the beaks not prominent, the ligament stout, the escutcheon 

 long, narrow, and deep. Length of adult shell 48, height 27, diameter 

 18 millimetres. The beaks are 11 millimetres behind the anterior end. 

 U. S. Steamer Albatross, station 3077, oft" Dixon Entrance, Alaska, in 

 322 fathoms. 



Limopsis vaginatus, sp. nov. 



Shell large, ovate, with a dense brown hirsute epidermis, under which 

 the valve is polished, radiately and concentrically striated; margin 

 simple, polished, central part of the valves striate radially, the muscular 

 scars bounded inwardly by a radial elevated ridge, most prominent be- 

 hind the anterior scar. Hinge with ten anterior and five posterior teeth, 

 separated by a gap, beaks little elevated, ligament wide, subtriangular 

 and black ; behind the hinge the cardinal margin is deeply folded in, ; 

 forming when the valves are shut a long, very narrow i)it more than 

 one-fourth as deep as the whole width of the shell at right angles to that 

 margin ; this pit is also densely hirsute. The outline of the shell margin 

 is thus made reniform. Length of shell with epidermis 34, height at 

 right angles to the hinge line 30, diameter 12 millimetres. Leugth of 

 pit 16 and depth 5.5 millimetres. U. S. Steamer Albatross, station 3330, 

 oft" coast of Unalashka Island, Bering Sea, in 351 fathoms, and south 

 of Unimak, in 80 fathoms, by W. H. Dall, in 1865. 



Washington, June 6, 1891. 



EEFERENCES TO PLATES. 

 Plate V. 



Fig. 1. Tropbon triangnlatus Carpenter, adult, T.'S millimetres; p. 180. 



2. Enpleura ninriciformis Broderip, typical form, 37.4 millimetres; p. 174. 



3. Trophon triaugulatus Carpenter, young shell, type specrmen, much enlarged, 



11.5 millimetres; p. 180. 



4. Enpleura caudata Say, var. sulcidentata Dall, type specimen, 19 millimetres; 



p. 176. 



5. Trophon cerrosensis Dall, type specimen, 38 millimetres; p. 181. 



6. Trophon triangnlatus Carpenter, adult, viewed from above, diameter 50 mil- 



limetres ; p. 180. 



7. Tropbon cerrosensis Dall, type specimen viewed from above, diameter 25 mil- 



metres; p. 181. 



