GENA. 437 



most numerous iu the Philippines, the majority having 

 been discovered iu those Islands by the indefatigable 

 Mr. Cuming; their favourite locality is on coral reefs, 

 but they are also found under stones at low-water. 



Species of Stomatia. 



acuminata, A. Adams. phymotis, Helbt. 



angulata, A. Adams. rubra, Lam. 



decussata, A. Adams. splenclidula, A. Adams. 

 duplicata, Soiv. 



Genus MICROTIS, A. Adams. 



Animal as in Stomatia, but the foot with a deep, anterior 

 fissure for the head, and with the front edge bilobed. 



Operculum none. 



Shell spiral, sub-orbicular, depressed, with two tubercu- 

 lated ridges ; spire slightly prominent ; aperture very large, 

 wider than long ; columellar margin spiral, visible as far 

 as the apex of the spire. 



Ex. M. tuberculata, A. Adams, pi. 50, fig. 1, 1, a, 

 I, h. Shell, M. tuberculata, fig. 1, c. 



The shell of Microtis resembles that of a little Hali- 

 otis without the perforations ; the foot of the animal being 

 fissured in front, and the spiral columella of the shell, dis- 

 tinguish the genus, of which there is but a single species 

 at present known. 



Genus gena. Gray. 



Animal sub-spiral, oval, depressed, too large to enter the 

 shell ; frontal lobes plumose ; foot very large, tubercular, 

 posteriorly produced ; lateral membrane not fringed, more 

 or less extended and partially covering the shell. 



