222 THE VOYAGE OF H.M.S. CHALLENGER. 



Circe castrensis, Circe trimaculata, and Circe cerina, will, I think, perceive the 

 gradual transition of one form into the other, and will be convinced that neither 

 Lioconcha nor Gouldia (as understood by Dall) should take generic if even subgeneric 

 rank. 



Mr. Dall states that " we do not know the animal of Circe." This is not correct, for 

 Deshayes (Proc. Zool. Soc. Lond., 1853, p. 171) has examined the soft parts of several 

 species belonging to the two principal groups of the genus "[Circe scripta, Linn., and 

 Circe testudinalis, Chemn.)," and figures the animal of Circe divaiicata. He observes 

 that " ces animaux ne different en rien de celui des Meretrix " and " de cette ideutite, 

 parfaitement constatee pour nous, entre les Meretrix et les Circe, nous concluons que ce 

 dernier genre doit rentrer dans le j)remier a titre de simple division ; en reuuissant les 

 especes des deux groupes on voit s'etablir entre elles one transition insensible dans la 

 transformation de formes exterieures." 



Romer, in his monograph of the genus Vcnu.^, regards Lioconcha as a " sectio " of 

 Cijtlierea, which is termed by him merely a subgenus of Ve)i us. Circe he also considers 

 a section in the same way. 



Gouldia parva, which I hold as the type of the genus, is considered by Dall to belong 

 to Eriphyla of Gabb, which is stated l)y Dall to 1je a subgenus or section of Crassatella. 

 This location of Erip)hijla cannot, however, be correct, if Gabb's description is to be 

 relied upon, for, besides an external ligament, that genus apparently has a different 

 hinge, and according to Stoliczka partakes more of the general character of certain forms 

 of Veneridse. Dall says that Gouldia parva and the like " differ from the typical 

 Crassatella chiefly in form, in the elongation and more distant location of the lateral 

 teeth, the usually unequal valves, and in their uniformly small size." Now, of these 

 points of distinction, I maintain that form and size are not generic or even subgeneric 

 characters, the inec[uality of the valves I fail to discover in the series of specimens in the 

 British Museum, and the difference mentioned in regard to the lateral teeth does not 

 appear to me to exist. In Crastsatella hingicola, which may be regarded as a typical 

 species, 1 find the posterior lateral teeth and those less pronounced on the anterior side, 

 extending from the upper end of the muscular impressions towards the umbones. This 

 too is constant in all the other species of the genus which I have examined, including that 

 under discussion, Crassatella parva of C. B. Adams. To show the absolute agreement of 

 this form with Crassatella, I would point out two minor features which I believe have not 

 as yet been referred to, namely, the coarsely striated character of the cardinal teeth and 

 the presence of a small deep distinct pedal muscular scar just above the anterior 

 adductor impression. 



A summary of the whole discussion and difference of opinion may be given in a few 

 words. 



I regard Goiddia parva as the typical species ; Dall holds to Gouldia cerina. \ 



