CAPULUS LFSSUS, SMITH, AS TYPE OF A PROPOSED NEW 

 SUBGENUS {MALLUVIU3I) OF AMALTHEA, SCHUMACHER. 



By James Cosmo Melvill, M.A., F.L.S. 



Rcad^th March, 1906. 



In 1894 Mr. Edgar Smith described^ an ab5^ssal mollusc, from the 

 Bay of Bengal, dredged during the cruise of H.M. Indian Marine 

 Survey steamer "Investigator," Commander C. F. Oldham, R.J^., at 

 a depth of 90-102 fathoms. To this he gave the name of Capuhis 

 lissHs. 



Since that date Mr. F. W. Townsend has procured, from various 

 stations in the Persian Gulf and Gulf of Oman, to be enumerated 

 subseq[uently, more voluminous material, including live examples 

 in situ, and exhibiting considerable variety. I know, therefore, tliat 

 the author will allow me to further extend his original description to 

 suit the larger specimens now before me, and also to propound reasons 

 for considering this species as rather appertaining to Amalthea, Schum. 

 { = IIi2)poni/x, Def ranee). 



Mr. Smith rightly lays stress upon the complete absence of radiating 

 sculpture. In all the species of either genus [Amalthea or Capulus) 

 known to me, this sculpture is present, and accordingly, to whichever 

 of these this mollusc belongs, that fact in either case attains equal 

 predominance. 



Mr. Townsend dredged C. lissus either dead, in shell-sand, mostly 

 small imperfect examples, at a considerable depth, or alive, on Rostellaria 

 delicatula, Nevill (Fig. 1), and especially Conus planiliratus, Sowb. 

 (Fig. 4). On this latter it was gregarious, forming colonies of life ; 

 and usually a small example is found to have attached itself to 

 the dorsal surface of, very probably, its parent. But the most 

 interesting discovery was that of a few examples obtained at 

 122 fathoms in the Gulf of Oman in 1903, when the larger ones 

 were found adhering to the spines of a Cidaris (Figs. 2, 3), 

 invariably attended by a small, but normally shaped, offspring, attached 

 dorsally, while they themselves had assumed a narrow oblong form, 

 having become adapted to the attenuate spine they had affected. 

 Contracted as they thus were, it was nevertheless necessar}^, as they 

 still overlapped considerably at the base, to deposit shelly matter, 

 formed out on both sides, thus creating a basal plate, of considerable 

 solidity and thicliness. This is a characteristic of the genus Amalthea, 

 Schum., rather than of Capulus, Montfort, as the foot of the latter 

 genus does not ever secrete a shelly base. 



Auu. & Mag. Nat. Hist., vol. xiv (1894), p. 1G6. 



