CYCLAS. 117 



variety, measuring occasionally seven lines by five and a 

 half, has been taken in Clumber Lake by Mr. Jeffreys. 

 That gentleman has likewise sent us for our inspection a 

 peculiarly aberrant specimen from Cork (entirely agreeing 

 with one taken by ourselves from a foul-smelling pool com- 

 municating with the river Lea ; S. H.), wherein the pro- 

 jecting umbones are not capped at all, but the contour is 

 precisely that of the preceding variety. In the two latter 

 forms, the edges (especially the ventral) are straighter than 

 usual, and the hinder dorsal edge is rather ascending than 

 otherwise. 



We have preferred, on reconsideration, the epithet 

 caliculata, bestowed upon this species by Draparnaud, 

 partly from its expressiveness, partly because that author 

 is said by Dupuy and others (we have not seen a copy 

 ourselves) to have published the name in 1801, in a Pro- 

 dromus to his posthumous and larger work, and partly to 

 avoid the confusion which our mention of .the C lacustris 

 of the continental writers among our less positively indi- 

 genous species, would otherwise induce. The Tellina 

 lacustris of Miiller (1774), which seems too imperfectly 

 defined for assured identification, is almost invariably 

 cited for the following shell. 



The animal, as observed by Mr. Jenyns, is entirely 

 white. Its siphonal tubes are much elongated, and resem- 

 ble those of cornea. The length of a fine individual was 

 seven lines, and its breadth five and a half. There are 

 two principal varieties ; the first, which is of a rufous 

 brown, is less pellucid and compressed and more rounded 

 in contour than the type ; the second, which resembles the 

 preceding in the other points of diversity, is of a reddish 

 cast, and displays but a slight degree of prominence at its 

 blackish beaks. 



