JOURNAL OF CONCHOLOGY. I93 



ON THE POSITION OF THE OPERCULUM IN 

 CONCHOLEPAS FERUVIANUS, Lam. 



By the Rev. A. H. COOKE, M.A., F.Z.S. 



Curator in Zoology, Museum of Zoology and Comparative Anatomy, Cambridge. 



Some ' living ' specimens of this fine shell having recently come 

 into my hands, the position of the operculum at once struck me 

 as being very remarkable, and I am not aware that it has hither- 

 to been noticed. Kiister, in his Monograph of the Purpuridae 

 in Martini and Chemnitz, ' Conchylien Cabinet,' 1858, Taf. A., 

 f. 3, gives a figure of the animal in motion, and so do H. and 

 A. Adams, ' Genera of the MoUusca,' vol. iii., pi. xiv., fig. 2. 

 Both these illustrations are copied from Kiener, Monograph of 

 Purpura,' pi. 23, fig. 65, and represent the animal in colours 

 whose brilliancy is wholly imaginary. The operculum is repre- 

 sented, no doubt rightly, in the ordinary position on a Purpura 

 in motion. 



The accompanying sketch ('Journ. of Conch.,' April, 1887, 

 pi. i., fig. 5) is an attempt to represent the animal in a state of 

 quiescence, as seen from the under side. Almost all that 

 presents itself is a very broad tough fleshy foot, standing out 

 from the mantle quite as much as the foot of an ordinary 

 Patella. The tentacles are small, almost hidden under the 

 front edge of the foot, while the proboscis works up and 

 down in the shallow groove of the canal. The mouth is almost 

 equal in length to the whole length of the shell. 



The operculum differs from most opercula which are too 

 small to cover the mouth, for it makes no attempt to cover it at 

 all. In the Strombidse and the Conidae the operculum by no 

 means fits the mouth, but it covers part of it, and lies in the 

 same plane. But in Concholepas the operculum lies across the 

 mouth, in a plane at right angles with its length,* and thus 

 assumes an entirely abnormal position. 



* The sketch shows a Httle too much of the surface of the operculum ; it 

 should lie more edgewise. 



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