844 PELECYPODA. [Filibranchia. 



triangular ; the upper byssus-scar tongue-shaped, slightly sinuate 

 below ; the second below it tangential, oval ; the adductor-scar below 

 and behind the latter, very close to it, subcircular. Foramen of the 

 right valve very large, concave in front and below, straight and 

 thickened behind ; the processes approaching, but leaving a fairly 

 wide space between the two. 



Length, 21 mm. ; height, 17 mm. (type from the Pliocene). Length, 

 53 mm. ; height, 53 mm. ; diameter, 9 mm. (left valve of the Recent 

 specimen from Stewart Island). 



Type, from the Pliocene, in the Canterbury Museum, Christchurch. 



Hob. Stewart Island ; one specimen. 



Remarks. The specimen in the Dominion Museum is quite distinct 

 from A. cytceum, with which I have compared it. 



Fossil from the Oligocene to Pliocene. 



4. Anomia Walter!, Hector, 1895. Plate 57, fig. 10. 

 Anomia Walter!, Hector, T.N.Z.I., xxvii. 1894 (1895), 292. 



Shell irregular in form, generally transversely oval, very inequi- 

 valve, inequilateral, thin, fragile, and translucent, somewhat nacreous, 

 and with a brilliant lustre when young ; adult shells are fairly solid, 

 and only faintly shining. The anterior or the posterior end of the 

 valves may be produced. Sculpture of left valve consisting of distant, 

 irregular, mostly interrupted, radiate ribs, crossed by inequidistant 

 concentric growth-lines ; right valve mostly concave, with concentric 

 laminae, and sometimes with distant radiate grooves. Colour : Left 

 valve rich honey-yellow, sometimes with pink tint ; right valve colour- 

 less in the young, green in the adult. Interior of left valve iridescent, 

 white with faint yellow and pink ; right valve with a broad wide 

 white crescent round the notch, the remainder green, the whole surface 

 polished. Margins usually sharp and undulating. The ligament in a 

 broadly triangular pit in the umbonal cavity. On the inner side of 

 the left valve a triangular area of white shell extends from the cartilage- 

 pit to the middle of the valve, containing above the rounded byssus- 

 scar with a nearly straight lower margin ; on the anterior two-thirds 

 and below it, separated only by a narrow space, is the second byssal 

 scar, which is smaller and oval ; close behind it and usually posterior 

 to the upper byssus-scar is the adductor-scar of the valves, very distinct 

 also in the right valve. The foramen is small, nearly circular, the 

 processes sometimes nearly meeting. Byssiferous plug calcified. 



Left valve : Length, 67 mm. ; height, 51 mm. ; diameter, 16 mm. 

 (medium size). Length, 91 mm. ; height, 75 mm. ; diameter, 20 mm. 

 (largest size). 



Type in the Dominion Museum, Wellington. 



Hab. Pahia, Bay of Islands (Th. Walter). 



Fossil in the Pliocene (teste J. Park). 



