506 mutelidjE. 



Anodontites, Brug. Iridina, Lam. Berpolis, Leach. 

 Euphira, Gistel. Platiris, part, Lea. 



Ex. M. dubia, Gmelin, pi. 119, fig. 1, 1, a. 



The species of Mutela are few in number, and are 

 African in their geographical distribution. 



Species of Mutela. 

 dubia, Gmel. valeus, Parr. 



Sab-gen. calliscapha, Swainsoii. 



Shell with the hinge-margin only slightly crenulated at the 

 umbones. 



ccelestis, Lea. Nilotica, Ferus. and Sow. 



Genus pleiodon, Conrad. 



Shell elongate-ovate, strong, convex, ventral edge much 

 arcuated, sides rounded, the anterior the broader and longer ; 

 valves covered with a dark, olive epidermis ; beaks usually 

 eroded. Hinge-margin sub-arcuated, becoming broad at 

 the extremities, furnished with large, tubercular crenations. 



Ex. P. ovatus, 8wainso7i, pi. 119, fig. 2, 2, a. 



The interior of the valves in this genus is covered with 

 an iridescent, silvery nacre, often tinged with pink. Two 

 species only are known, from Africa. 



S'pecies of Pleiodon. 

 Leuii, Sow. ovatus, Swains 



