876 PELECYPODA. \Filibranrhia. 



1 to 3 radial fine riblets may be present ; besides this sculptuie there 

 are minute divaricating radial lines (the so-called Camptonectesstriation). 

 The concentric sculpture consists of very fine and rather close undu- 

 lating and slightly imbricating layers. Colour of right valve whitish, 

 lightly tinged with pink, rarely yellowish-brown all over ; left valve 

 always much darker coloured, white with red concentric spots and 

 bands, or reddish or yellowish-brown, sometimes mottled with white. 

 Inside shining, white or stained with red, strongly grooved, the margins 

 dentate or crenulate. Hinge-line straight, with distinct cardinal crura. 

 Resilifer triangular, not very deep, its margins rather sharply raised ; 

 external ligament narrow and long. 



Diameter Ant. -post., 32 mm. ; dorso-ventral, 36 mm. : thickness, 

 10 mm. 



Type in my collection. 



Hob. A number of valves were found in the stomach ot a blue- 

 cod (Parapercis colias, Forster) caught in Port Pegasus. Stewart Island, 

 and kindly given to me by Captain Bollons. East of Jones Head, 

 in 20 fathoms ; 19| miles south of Oamaru, in 40 fathoms ; off 

 Lyttelton, in 100 fathoms (E. R. Waite). 



Remarks. This species is allied to the Miocene Pecten chathamensis, 

 Hutton (C. Tert. M., 29), but this species has the ribs more scaly, 

 the scales more distant ; the ribs show no tendency to division towards 

 the margins. The anterior ear of the right valve is not large, has no 

 byssal sinus, and there is, of course, no ctenolium. The form and 

 size, of the shell and the number of ribs are about the same as in the 

 Recent species. 



3. Pecten imparvicostatus, Bavay, 1905. Plate 58, figs. 9, a. 



Pecten imparvicostatus, Bavay, J. de Conch., liii, 1905, 23, pi. 2, f. 6, 7 ; 



Suter, T.N.Z.I., xxxviii, 317 ; not P. australis, Hutton, J. de Conch., 



xxvi, 54, nor P. asperrimus, Hutton, P.L.S. N.S.W., ix, 531, both being 

 no doubt P. gemniulatus, Reeve. 



Shell of medium size, rather solid, moderately convex, inequivalve, 

 subequilateral. Beaks approximate, the prodissoconchs minute, tri- 

 angular, smooth. Ears very unequal, the margins denticulate ; an- 

 terior ears high and large, that on the right valve with a byssal 

 sinus ; posterior ears short and small. Left valve more convex than 

 the right, which has a ctenolium at the byssal notch. Discs highly 

 triangular, the anterior and posterior sides descending straight toward 

 the regularly rounded basal margin. Sculpture : Anterior ear of 

 left valve with 6 to 10 unequal squamose radial riblets, that of the 

 right valve divided into an upper area with about 7 squamose radial 

 costse, and a lower byssal area with transverse lamellae ; posterior 

 ears with 5 to 7 squamose riblets ; left valve with 11 elevated sub- 

 equal ribs, alternately stronger and more feeble, the insterstices broader 

 than the ribs, with a median more slender rib, and the secondary 



