Although it is almost ccrtMin that this shell is nothing more thun the 

 adult stage of the preceding species, it has "been thought better to 

 describe the two specimens separately. Both are broad in front and 

 narrower behind; thej agree, also, in other characters, snch as the 

 absence of a delined lunule, and the shape of the escutcheon. The only 

 difference of an}- consequence is the position of the beaks, which are 

 placed behind the centre in Ihe small specimen, and a little in advance 

 of it in the large]- one. But i\Ir. Meek's figures of different specimens 

 of L. subunddtii and L. ventrico&a show that these two species vary in a 

 precisely similar Avay. The same writer doubts whether L. subundato, 

 L. occidentfdis and L. ventncosa are more than varieties, or different 

 stages of growth, of one species, and it certainly seems probable that 

 such may be the case. The larger of the two Luclnce from the Queen 

 Charlotte Islands has almost exactly the shape of one of the specimens 

 of L. ventricosa as represented by Meek, (Eeport cited, Plate XVII., 

 fig. 3, b, bis.,) except that the beaks of the latter are placed behind the 

 centre, and that its posterior end is sub-truncate. 



CaLLISTA (?) SUBTRIGONA. (N. Sp.) 

 Plate IX., fig. 10. 



Shell moderately compressed, ovately triangular, bluntl}^ pcjinted or 

 subangular about the middle in front, and a little below it behind ; 

 length rather greater than the height ; test very thin. 



The beaks, which are placed at about (Uie-fonrth of the distance fi'c^m 

 the anterior end, are of medium size; their apices are directed forwards, 

 and sunk a little below the highest level of the hinge line. There is 

 no hnuile, and the escutcheon is a narrowly lanceolate groove with 

 almost vertical sides. The posterior half of the shell is somewhat 

 produced and sub-angular l)elow the middle ; the superior border behind 

 and the margin of the postei'ior end are united in one bold and 

 unbroken convex curve, which extends from the beaks to the ventral 

 margin. The downward direction of this curve is, howevei*, most 

 decided below the termination of the hinge line. The basal margin 

 is broadly but unevenly rounded, the front half being most projecting and 

 the hinder half rather more contracted. Below the beaks, in front, 

 the superior border descends obliquely in a straight or slightly convex 

 line, and forms a sub-angular junction with the ventral border at the 

 centre of the anterior end. 



