122 PEOCREDINGS OF THE MALACOLOGICAL SOCIETY. 



' NOTE ON THE SUBGENUS MALLUVIVM, MELVILL. 



By Edgar A. Smith, I.S.O. 



Read \lth May, 1906. 



In the last part of these Proceedings (p. 81) Mr. Melvill has made 

 some observations upon the genera Amalthea of Schumacher and Capulus 

 of Montfort, and has created a new subgenus of the former to include 

 a species described by me as Capulus lissus. I do not agree with the 

 conclusions he has arrived at, hence the few following remarks. 



Schumacher included two species in his genus Amalthea, namely, 

 A. cornea {= Patella australis, Lamk.) and A. maxima (=the well- 

 known Capulus hmigarimis). The latter had already been appropriated 

 by Montfort for his genus Capulus, and therefore Amalthea is typically 

 represented by the first species, A. conica. 



The account of the animal of this species given by Quoy & Gaimard 

 (Voy. xistrolabe, ZooL, vol. iii, p. 434, pi. Ixxii, figs. 25-34) shows 

 that it is practicall}^ of the same character as that of Hipponyx 

 antiquatus (see Fischer, Man. de Conch., p. 753, fig. 519), which is 

 the type of that genus, for " E. mitrata, Gmelin," as quoted by 

 Defrance, the author of the genus Hipponyx, is presumably merely 

 a misprint of mitrula, Gmelin, which is synonymous with 

 H. antiquatus. "With regard to Amalthea, Messrs. H. «& A. Adams 

 observe that it is "like Concliolcpas \^= Riiiponyx'], but it simply 

 excavates with its foot a supeificial cavity in the surface of the shell 

 or stone on which it fixes itself, not forming a shelly plate distinct 

 from the substratum." 



Such, however, is not invariably the case, for sometimes a shelly 

 base, although it may be thin, is certainly secreted. It is also stated 

 by Dr. Turton that he had in his collection a specimen of Capulus 

 hungaricm which had formed "a thin laminar under-valve," but 

 Jeffreys thought he must have been mistaken. His account of the 

 circumstance, however, is so exact that I see no reason to doubt it. 



Try on observes concerning Hipponyx, "the same species will either 

 excavate a cavity to which it adheres, or secrete a testaceous support." 

 Seeing, therefore, that the same species of Amalthea, and perhaps 

 Capulus also, either may or may not construct a shelly basal support, 

 this cannot be regarded as an essential generic feature. 



The Capulus lisms upon which Mr. Melvill has founded his 

 subgenus Malluvium appears to form a thickened shelly base only 

 under exceptional circumstances. On a specimen of Rostellaria 

 delicatula from the Bay of Bengal it has formed a scar on the surface, 

 and only secreted a film of callus and a slight thickening at the edge 

 of the depression. The fact of its being smooth, instead of radiately 

 striated like other species, does not seem to me of subgeneric value, 

 nor do I regard the presence or absence of colour-rays of any 

 importance. 



