MYA. 169 



Ckama arenaria. Da Costa, Brit. Conch, p. 232, 

 Mye dns sables, Chem, Traite Eleni. p. 48, f. 149, 150 (hinge). 

 Mya niei-cetiaria, aiid M. acuta. Say. J. Ac. N. S. Phikd. vol. ii. p. 313 (fide de 



Gould). 



This coarse and homely-looking shell has an oblong-oval 

 contour, and a strong and solid textui'e, so as not un- 

 frequently to be of considerable Aveight. The valves, 

 which when most perfect have an ochraceous tint or are of 

 a darker or paler sand colour, are frequently stained black, 

 owing to the nature of the soil in which they are embedded; 

 they are not uncommonly distorted or irregular in their 

 growth, and are more or l6ss ventricose, particularly upon 

 the anterior side. Their surface is entirely devoid of 

 lustre, and is rudely traversed concentrically by irregular 

 Avrinkles and lines of increase. The ash-coloured epider- 

 mis is but thinly spread over the surface, and is often 

 entirely obsolete, or only visible towards the ventral mar- 

 gin. This latter is more or less retuse a little behind the 

 middle, slightly convex posteriorly, and ascending and 

 arcuated anteriorly. The sides are almost equal, the 

 posterior, if either, being rather the longer, and bluntly 

 acuminated below at its termination ; the front side, which 

 is also the more ample one, is nearly equally rounded above 

 and below at its extremity. The front dorsal edge, which 

 is convex or even arcuated, declines but slightly, the 

 hinder, which is produced and comparatively straight, 

 though still somewhat convex, is decidedly sloping. The 

 umbones are by no means peculiarly prominent, and are 

 often flattened above ; the beaks are sometimes almost di- 

 rectly inflected, but more generally incline forwards; there 

 is no vestige of an impression on either side of them ; 

 neither is there any distinct umbonal ridge. The shell 

 gapes at both extremities, but much more so upon the 

 narrower side, where neither the upper nor lower edges 



VOL. I. z 



