84 LAMELLIBRANCIHATA. 



plug shelly at the top and near the body to which it is attached, and 

 with horny longitudinal 1 ami use below and internally. 



Europe. Kamtschatka. California. West Indies. Australia. 



129. P. zealandica, Gray, Dief. N.Z., i\.,p. 280. Sub-orbicular, 

 white, smooth ; upper valve with distant radiating grooves ; internally 

 dark green; upper valve with two confluent scars; upper oblong, 

 longitudinal, lower rather small and more transverse; thin, trans- 

 lucent. Diameter, 1'75. 



Stewart's Island. 



130. P. ione, Gray, Proc. Zool Soc., 181-9, p. 123. White, 

 laminar ; edge of the lamina? with small, slender, elongated processes ; 

 interior green ; lower muscular scar small, round, on the lower hinder 

 edge of the larger one ; sinus or perforations large. Diameter, 2 '4. 



Stewart's Island. Australia. Tasmania. 



FAMILY OSTEREIDJE. 



Inequivalva, inequilateral, irregular, close and fixed by the inferior 

 valve, which is the largest, or free; beaks central, straight; adductor 

 impression single, behind the centre. 



OST&EA. 



Irregular, attached by the left valve ; upper valve flat or concave, 

 often plain ; lower convex, often plaited or foliaceous, and with a 

 prominent beak ; ligameutal cavity triangular or elongated ; hinge 

 toothless. 



Tropical and temperate seas. 



131. O. purplirea, Hanley, Condi. Miscel., pt. 3. Ovato-or- 

 bicular, upper valve flat, laminated with imbricating scales; lower 

 rugged, wrinkled; ligament pit small, triangular ; muscular impression 

 large, lunate, scarcely hollowed. Purplish, white near the hinge; 

 interior yellowish or greenish white, margin purple, waved. Diameter 

 about 2. 



Common. The shore or small mud oyster. Australia. 



132. O. lilt aria, sp. nov. Orbicular, upper valve generally con- 

 cave, smooth, with imbricating lamina? round the margin ; lower valve 

 smooth, margin waved, thick ; ligament pit triangular, muscular im- 

 pression very large, lunate, sub-medial, not hollowed. White, interior 

 greenish. Diameter, 4. 



Pelorus Sound. Catliu Eiver. 



133. O. Virginica, LamarJc, I.e., vii., p. 225. Oval or orbicular, 

 irregular ; upper valve rather convex ; thick ; lower rugged, with im- 

 bricating plates. Upper valve brownish, lower generally white; interior 

 brownish. Diameter, 2 to 4. 



Chatham Islands. North America. Brazil. 



134. O. Hiordax, Gould, Proc. Boston Nat. Hist. Soc., iii., p. 340. 

 Thick, irregular, lower valve plicated and rugose with spinous processes; 

 upper valve flat, slightly plicated at the margin ; ligament pit large 



