A412 MOLLUSCA. 
correspond in form, sculpture, and other characters. It comes near to 
Donax cuneata, but is still nearer to Mesodesma striata in general 
aspect. 
Figures 521, 521 a, lateral and dorsal views of the shell. 
Donax crocatus (Gould). 
Testa parva, tenuis, transversa, ovato-triangularis, inequilateralis, dilute 
crocea, concentricé lamelloso-sulcata ; latere antico semi-ovato ; latere 
postico breviort, arcuatim-truncato; margine ventrali lente arcuato : 
intus flavida, nitida ; cardine valido. 
Donaz crocatus, Goutp; Proceed. Boston Soc. Nat. Hist., i. 255. 
June 1850. Expedition Shells, 82. 
SHELL minute, thin, compressed, convex, transversely elongate, 
ovate-triangular, inequilateral, concentrically lamellar sulcate, of a pale 
saffron-colour, with minute transverse lineations of a darker colour ; 
outlines rounded; beaks not quite at the posterior third, dorsal outline 
forming an obtuse angle; anterior end acutely ovate; siphonal end 
obtusely rounded, somewhat truncate: ventral margin slightly arcuate. 
Interior yellowish, shining, hinge well developed. 
Length two-fifths of an inch; height one-fourth of an inch; breadth 
three-twentieths of an inch. 
Inhabits Mangsi Island, Sooloo Sea. 
This small species is sufficiently well characterized, and is some- 
what like D. scalpellum. 
Figures 522, 522 a, lateral and dorsal views of the shell, magnified ; 
522 6, natural size. 
Luctna INcuLTa (Gould). 
Testa tenuts, lenticularis, retrorsum admodum obliqua, stramineo-allida, 
