ACEPHALA. AO] 
Length three-fourths of an inch; height five-eighths of an inch; 
breadth three-tenths of an inch. 
Inhabits Mangsi Island, Sooloo Sea. 
Distinguished from M. striata by its more compressed, less angular 
form, its short, broad, rounded anterior end, there being no angle ex- 
cept at the beaks, and by its smooth surface. It may also be com- 
pared with M. glabella, Deshayes. 
Figures 511, 511 4a, lateral and dorsal views of the shell; 5118, the 
hinge. 
Eryctna (Poronta) ovata (Gould). 
T. parva, alba, nitida, concentrice striata, ovato-ventricosa, tnequilatera- 
ls; margine cardinali arcuato ; umbonibus parvis, antemedianis ; 
margine ventral parum arcuato ; latere antico truncato ; latere pos- 
tico rotundato ; valve. dextre dente cardinali erecto, bifido ; fovea liga- 
mental parva ; valve sinistre dente integro: intus alba. 
Erycina (Poronia) ovata, Goutp; Proceed. Boston Soc. Nat. Hist., 
ill. 218. E:xpedition Shells, 78. 
SHELL small, thin, ventricose-ovate, inequilateral, shining, concen- 
trically striate, and very minutely radiate-striate. Hinge margin 
rounded, the beaks a little before the middle, small, not prominent: 
basal edge but little curved ; posterior end well rounded ; anterior end 
truncate, a little obliquely. Hinge delicate, with a minute cardinal 
tooth, bifid in the right valve ; lateral articulation but little developed ; 
ligament pit small. Interior white. 
Length three-twentieths of an inch; height one-fourth of an inch; 
breadth one-fifth of an inch. 
Inhabits the Sandwich Islands. 
Differs from the next species in its smaller size, more inequilateral 
and ventricose form, shining surface, and delicate hinge. 
10] 
