Airr. 17 ILLUSTRATIONS OF TYPES OF SHELLS DALL 31 



surface; aperture narrow, outer lip thin, sharp; body erased; pillar 

 slightly concavely arcuate, attenuated in front, the axis pervious: 

 canal hardly differentiated from the aperture ; height of shell, 41 ; of 

 last whorl, 27; diameter, 14 mm. U. S. Nat. Mus. Cat. No. 110770. 



Dredged in Aniwa Bay, Sakhalin Island, by the United States 

 Bureau of Fisheries steamer Albatross, at station 5009, in 25 

 fathoms, mud, bottom temperature 38.5° F. 



The operculum has a slightly coiled nucleus approaching that of 

 Mohnia, but the habit of the shell is that of the elongate Volutopsius. 



VOLUTOPSIUS ROTUNDUS Dall 



Plate 6, fig. 4 



Volutopsius rotundus Dall, Proc. U. S. Nat. Mus., vol. 56, No. 2295, p. 310, 

 1919. 

 Kodiak Island, Alaska. U. S. Nat. Mus. Cat. No. 206350. 



VOLVULA ASPINOSA Dall 



Plate 25, fig. 5 



Volvula aspinosa Dall, Bull. Mus. Comp. ZooL, vol. IS, p. 51, 1889. 

 Off Cape Hatteras, N. C. U. S. Nat. Mus. Cat. No. 95302. 



VOLVULA BUSHII Dall 



Plate 25, fig. 3 



Volvula Mshii Dall, Bull. Mus. Comp. Zool., vol. IS, p. 51, 1889. 

 Off Cape Hatteras, N. C. U. S. Nat. Mus. Cat. No. 95301. 



WILLIAMIA VERNALIS Dall 



Plate 27, figs. 3, 5 



Siplionaria vernalis Dall, Amer. Journ. Conch., vol. 6, p. 38, 1870. 

 Monterey, Calif., on kelp. U. S. Nat. Mus. Cat. No. 32596. 



YOLDIA (CNESTERIUM) EXCAVATA, new species 



Plate 19, fig. 2 



Shell rather large, olivaceous in darker and lighter concentric 

 zones, with a brilliant periostracum; inequilateral, equivalve, some- 

 what attenuated posteriorly and slightly rostrate ; surface except on 

 the dorsal aspect of the rostrum, deeply and sharply sculptured with 

 oblique groovings; beaks inconspicuous, the lunule compressed and 

 vertically produced; the anterior slope gently curved, the anterior 

 end rounded, the base evenly arcuate, the posterior dorsal slope 

 slightly concave, the posterior end pointed and slightly recurved; 

 posterior hinge teeth about 15, anterior series about 27; the resilifer 

 large, the pallial sinus large and rounded; total length, 40; beaks 

 in front of the posterior end, 17; altitude at the beaks 20; diameter, 

 8 mm. U. S. Nat. Mus. Cat. No. 249337. 



