458 W. IT. Dall — Pliocene Conditions at Nome, Alaska. 



tions of obsolete radial threads, flattish and about a millimeter 

 in width ; submargins showing minute traces of vermicular, 

 scaly, minor sculpture ; byssal ear large, concentrically rugose, 

 with a broad, concavely striated byssal fasciole, above which 

 are four or five shallow radial grooves ; ctenolium short with 



six denticles ; posterior ear small, with about four faint radial 

 grooves; hinge line straight; internally with a rather large 

 ligamentary pit and muscular scar ; interior of the disk smooth ; 

 color of the shell apparently yellowish-red originally. Alt. of 

 shell, 61 ; lat. of shell, 55 ; do. at ctenolium, 25 ; do. at hinge 

 line, 30 mm . (Fig. 1, seven-ninths natural size.) 



Fifty feet below the surface in marine gravels near Nome, 

 Norton Sound, Alaska, Moffit, II. S. K Mus. 110480. 



