404 ciiiTOMia. 



and of nearly equal size throughout. The ligament i- rather 

 narrow, and arenaceous or minutely farinaceous. 



Mr. Lowe has remarked, that the margin oi' insertion in 

 the separated valves exhibits two nearly equal teeth on 

 each side upon the middle plates, twelve upon the last, and 

 about ten upon the first. These characters may prove 

 useful as subsidiary aids in the identification ot' the species. 



The red variety, which, as far as our own experience 

 goes, is usually the inhabitant of deeper water than the 

 greenish or olivaceous type, which latter is very abundant 

 under smooth stones, near low-water-mark, upon most 

 parts of the English coast, displays a coarser and more 

 prominent sculpture upon its valves, and larger granules 

 upon its ligamental margin. 



The monstrosity C. quinqucvahis (Browx, 111. Conch. 

 G. B. p. 66, pi. 21, f. 2'2) probably belongs to this species. 



The soft parts of the animal are of a general dusky 

 flesh colour, except the centre of the foot, which is deeply 

 tinged with livid blue. The under-margins of the mantle 

 are of a pale flesh colour. The hood or veil of the head 

 is narrow. There are from fifteen to eighteen branchial 

 leaflets on each side, all of a dusky flesh colour. Each 

 range of branchiae extends from behind forwards rather 

 more than two-thirds of the length of the body. The 

 lingual ribband is slightly shorter than the length of the 

 body, but rather wide, and in a middle-sized specimen 

 we counted eighty transverse rows of lingual teeth, which 

 for the greater part of its length are tinged with bright 

 yellow. The axile denticle is linear, slightly widened 

 at its extremity, and colourless, and resembles that de- 

 lineated by Loven in his representation of the teeth of 

 asellus. 



This very common species is distributed all round our 



