4(j solenidtE. 



latus, in some obvious particulars. He makes no mention of the 

 fringe of flesliy teeth along the margin of the mantle, which are so 

 remarkable, and which are probably retractile. The branchiae do 

 not enter the siphon ; the foot is not linguiform, but somewhat club- 

 shaped, and bent at a right angle within the shell ; and the siphons 

 are united entirely to their extremities, though the branchial is 

 slightly more elongated than the anal siphon. 



This genus embraces, besides the two species here described, the 

 Solen radiatiis, Lin. (^Solecurtus lucidus, Conrad), Solen iriaximus. 

 Wood {Solecurtus NuttalUi, Conrad), Solen injlexus, Wood, and *S'. 

 pellucidus of Europe. These accord with our shells in all respects, 

 except that the third tooth of the left valve in some of them is re- 

 placed by a marginal elevation simply. They differ in their ovate 

 and compressed form from Solecurtus, and especially do they differ 

 from sul)-genus CulteUus by ha^dng the beaks placed anteriorly. The 

 sinus of the pallial impression usually extends about half-way to the 

 hino;e. 



'O^ 



Machsera squama. 



Figs. 25, 26. 



Shell slightly i-ecurved, thick, white, undulated by the lines of growth, covered 

 with a strong, greenish-yellow, shining epidermis, corrugated at the posterior 

 extremity. 



Solecurtus squama, Blainv. Diet, des Sc. Nat. xlix. 419. — Des Moulins, Actcs do la 



See. Lin. de Bordeaux, v. 108 (18.32). 

 Machcera squama, Stimpson, Sh. of New England, 22. 

 Machcera nitida, Gould, Invert. 1st ed. 33 (1841). 

 Solen nitidus. Coll. Delessert, Chenu, Illust. Conch, pi. 8, fig. 1. 



Shell thick, white, oblong-ovate, beaks small, situated at the an- 

 terior fifth of the shell, narrowed behind, rounded at both extremi- 

 ties ; the hinge-margin is straight and somewhat compressed, and 

 the basal margin, being at the same time regularly curved, gives the 

 shell a somewhat recurved aspect. Epidermis thick, shining, as 

 if varnished, of a dusky greenish-yellow or dark gamboge color, 

 wrinkled ol)liqucly at the posterior extremity, and projecting be- 

 yond and folding around the edge of the shell. Lines of growth 

 broadly and prominently rounded, giving a wavy appearance. 

 Within white and strengthened by a prominent rib, which extends 

 from the beaks, inclining very slightly backwards, and, expanding, 

 loses itself in the shell about half-way across the valve. Hinge 

 having the teeth seated upon the base of the rib ; in the left valve 



