892 PELECYPODA. \_EuLamellibranchia. 



6. Ostrea reniformis, Sowerby, 1871. Plate 57, fig. 7. 



Ostrea reniformis, Sowerby, Conch. Icon., xviii, 1871, p!. 24. f 57 ; Hutton, 

 J. de Conch., xxvi, 56; M.N.Z.M., L75 ; P.L.S. N.S.W., ix. 533. 

 Index, 93. 



Shell thick, elongated, narrow, laterally arched, whitish, inequi- 

 valve ; upper valve compressed, flattened, a little leafy towards 

 the margins, edged within with purple ; lower valve deeply exca- 

 vated, ventral margin straight, muscular impressions blackish-purple. 

 (Sowerby.) 



Type in the British Museum. 



Hob. Unknown. 



lt< marks. In my collection there are specimens which to some 

 extent agree with Sowerby's diagnosis and figures ; they cannot be 

 assigned to any of the New Zealand species enumerated, and it seems 

 to me, anyhow for the present, preferable to refer them to (). reniformis, 

 although we cannot say where the type was found. In outline and 

 form of the valves they correspond fairly well with the figures, but the 

 margins are not edged with purple within, and the adductor-scars are 

 not blackish-purple, but dark olive ; both valves are olive-coloured on 

 the inner side ; the anterior and posterior dorsal margins of the right 

 valve are distinctly crenate, but this character seems to be lost in old 

 shells. The adductor-scars are semicircular, a little below the dorso- 

 ventral middle and posterior. A good series of these oysters should be 

 compared with the type. We know next to nothing of the influence of 

 environment on individual specimens of the New Zealand species, but 

 it seems highly probable that extended observations in tnis direction 

 may lead to a reduction of species. 



Hab. Auckland Harbour (H. 8.). 



Fam. PINNID/S, Meek. 



Animal dimyarian, with a very small anterior adductor muscle. 

 Foot byssiferous. 



Shell mytiliform, not winged, dimyarian. the anterior adductor- 

 scar smaller ; equivalve, truncate, and wholly open behind ; edentulous ; 

 area linear ; ligament parivincular, internal ; shell-structure coarsely 

 prismatic, with a thin partial nacreous lining. 



Devonian to Recent. 



Genus 1. ATRINA, Gray, 1840. 



.llriufi, <Jiay, Synopsis Brit. Mus., 1840. Type: Pinna niyra, Chenin. 



Animal having the foot conic, elongated, byssiferous ; labial palps 

 moderately large, elongated ; the small anterior adductor of the valves 

 under the beaks, the large posterior adductor subceiitral ; retractor 

 of the byssus large, in front of the posterior adductor. 



