272 TELLINIDiE. 



almost invariably mottled, and indeed this speckled ap- 

 pearance not unfrequently pervades the white rays also. 

 The ventral margin is, for the most part, nearly straight, 

 but is moderately convex and sharply ascending in front. 

 The dorsal edges possess but little convexity ; the front 

 indeed is inclined to retusion, and is scarcely at all sloping; 

 the hinder declination likewise, although greater, is but 

 very moderate. The anterior side, which is decidedly the 

 narrower, is well rounded at its extremity. The posterior 

 termination is very bluntly biangulatcd, the hinder edge 

 being distinctly convex, and the angles (particularly the 

 lower one) rounded off. The ligament is very large, dusky 

 brown, and prominent ; the beaks are small, and not at 

 all projecting ; and the umbonal ridge is quite obsolete. 

 In most specimens the inner surface is highly polished, and 

 of a porcelain white ; it is sometimes, however, (as in 

 foreign examples,) richly tinted with yellow or purple. 

 The hinge consists in the right valve of a very strong 

 simple broadly based anterior tooth, and a less solid, 

 narrow-based posterior one ; in the left valve, of an ex- 

 actly central rather narrow bifid tooth, with a very ob- 

 lique simple laminar posterior one, which latter is so 

 extremely thin and fragile as generally to be wanting in 

 our cabinet specimens ; from which circumstance this spe- 

 cies is usually described as having only a solitary tooth in 

 one of the valves. 



The average size of the valves is about two inches in 

 length, and rather more than one inch in breadth. Young 

 specimens are usually of an uniform pale yellowish hue, 

 with their ligaments of a yellow brown. Those mentioned 

 by Montagu as adorned with a more vivid colouring than 

 the adult, were, in all probability, the species subsequently 

 caWad Jforida by Dr. Turton. 



