OP CONCHOLOGY. 149 



The foot of Scurria mitra, Esch,, is oval, thin, smooth, and, 

 like all the soft parts in life, of a livid white color. The edge of 

 the mantle is complete, thickened and simple. The hood is 

 generally perforated over the gill. There are no papillae, ten- 

 taculjB, or anything of a like nature between the edges of the 

 foot and mantle. The tentaculge are long, rounded, with small 

 black eyes on the outer bases. The muzzle or rostrum is short, 

 provided with a well developed sucking disk around the mouth, 

 with a rough surface and a continuous edge. Outside of this 

 edge the outer edge of the rostrum forms a fold, which is termi- 

 nated at either side by a round and conical papilla. The gill is 

 laminar, triangular, thick ; under the hood, out of sight ; but 

 points across the neck from right to left diagonally. 



For details of dentition see fig. 5, A, from a specimen dredged 

 in 4 fms. stony mud ; Coal Harbor, Ounga Island, Alaska. Soft 

 parts fig, 5, c, from a specimen from Monterey, Cal. Fig. 5, b, 

 shell. 



Plate 15. — Explanation of figures. 

 Fig. 1. Lepetacceca, Gray. 



a, dentition (specimen from Norway). 



b, profile of do. 



c, extremely young magnified four times linear, showing the' 

 nucleus lying flat on the apex. 



d, shell, profile and outline, natural size. 



Fig. 2. Cryptohrancliia concentricay Midd» 



a, dentition (specimen from Sitka). 



b, profile of do. 



c, animal in situ from below. 



d, animal removed from shell, from above, 



(Posterior a little fore- V' ™^"^^^ ^^S^.'"^' ™"f ^^ ' ^' ^"' 

 shortened.) \ ^''''^', ^ ^, liver and ovary ; ., 



' ) genital and anal papilla. 



e, profile and outline of shell, natural size. 



f, buccal plate, magnified, g, muzzle from in front, magnified. 



Fig. 3. Cryptohrancliia alba, n. s. 



a, dentition. 



b, profile and outline, natural size. 



c, animal in situ, natural size. 



d, front vieWy mantle raised, magnified. 



11 



