58 CORBULID^. 



Isles to the ^gean and Canaries^ at depths of from 4 to 

 80 f. 



Oui" northern shores seem to produce the largest 

 specimens, those from the Channel Isles being more 

 brightly coloured. The fry have a squarish outline, 

 and are highly polished. This species varies both in 

 shape and sculptui'e, from oval to round, and from 

 ribbed to smooth. The shell is subject to the attacks 

 of predatory mollusks, which do not always succeed in 

 perforating it ; in such cases the white outside layer 

 only is removed, exposing the succeeding layers, which 

 are of a firmer texture and coffeecoloured. Aucapitaine 

 states that he found specimens of a smaller size and 

 paler colour than usual, living abundantly in brackish 

 water at Rochelle, often floating on grasses half covered 

 with water, and sometimes buried in mud to the depth 

 of their siphons. 



It is the Cardium striatum, &c., of Walker, My a in- 

 aquivalvis of Montagu, Corbula nucleus of Lamarck, and 

 C. olympica of Costa ; several other specific names have 

 been given to it by palseontologists. 



Among the shells collected by Mr. J. D. Humphreys 

 at Cork were a few specimens of C. mediterranea, Costa, 

 mixed with C. gibba. Philippi referred this species to 

 the Tellina parthenopcea of an unpublished work by 

 Delle Chiaje; and it appears to be also the C. physoides 

 of Deshayes''s ^ Mollusques d^Algerie.'' The Irish speci- 

 mens may have been imported (as well as Petricola 

 lithophaga) in ballast, and I therefore merely indicate 

 the possibility of its being indigenous ; but this species 

 is interesting in connexion with another shell, which I 

 have now to mention. In the ^ Malacologia Monensis ^ 

 of Forbes will be found a short description, but charac- 

 teristic figure, of a species named by him C. ovata. It 



