378 MOLLUSCA. 
Figure 479, the animal, as seen from below. 
LEPTOCONCHUS MADREPORARUM (Sowerby), Gould. 
Purpura monodonta, Quoy and Gaimarp; Voy. de l’Astrol., pl. 37, 
f. 9-11. Purpura madreporarum, Sowerby ; Genera No. 42; Reeve; 
Conch. Icon., f. 69. 
ANIMAL with its mantle lining the whole shell; ciliated at the mar- 
gin, with an anterior fissure in front of the head. The foot is small, 
being about half the length and breadth of the shell, oval; in front of 
the foot are two cervical appendages, meeting broadly at the median line, 
and tapering to each side. Head very narrow, elongated, with a longi- 
tudinal, oval cleft below; it is apparently incapable of being advanced 
to the edge of the shell. Tentacles large, long, subulate; the eyes 
without pedicles near the terminal third. Foot deep orange-co- 
loured ; cervical appendages roseate; head and tentacles lemon- 
yellow. Eyes black. Mantle very densely and beautifully dotted 
with lilac. 
It is to be regretted that no notes were to be found concerning this 
interesting animal, and that we are left entirely to the figure for the 
above characters. Indeed, it was for along time doubtful to what 
shell the animal belonged, until, happily, the identical shell figured 
in outline with the animal, was found, and proved to be a very small 
and distorted specimen of the shell, well known in most cabinets 
under the name of Purpura monodonta or madreporarum. It is 
plainly not a Purpura, and allied to the genus Crepidula rather than 
to Purpura. I have ventured to place it under the genus Lepto- 
conchus, which has also been grouped with the Purpurade, because 
the shell is very like the only species of Leptoconchus yet designated. 
At any rate, the animal is so peculiar as to justify its removal from 
Purpura, and to give it generic rank. 
The shell figured was found among corals at Wake’s Island, and the 
species is common throughout the low islands to the Samoa Islands. 
It is obviously often variously distorted, to accommodate itself to the 
fissures among the coral where it lives. 
