730 STUDIES ON AUSTRALIAN MOLLUSCA, 



Chlamys fenestrata, n.sp. 

 (Plate xlviii., figs. 17-19.) 



Shell small, very solid, convex, almost equilateral and equivalve, 

 inferior margin well rounded. Both auricles well developed, 

 angular, with a few faint radii. Colour rose with irregular white 

 splashes. Sculpture : the central third of the valve is occupied 

 by a deep and broad furrow flanked by two broad and high 

 ridges. On either side of these are two comparatively insignifi- 

 cant ridges with their complementary furrows. Each main 

 radius and sulcus has three or four secondary radii, those in the 

 hollows smaller and wider apart. The whole surface of the valve 

 is microscopically ornamented by fine, close, raised threads which 

 cross the radials at right angles. Fig. 19 shows a portion of the 

 central furrow highly magnified. 



The interior is stained deep rose. The adductor scar is deep. 

 The impress of the main radii extend as furrows to the umbo, 

 while the secondary radii merely denticulate the margin. The 

 left valve develops a few pectinidial teeth. The chondrophore 

 lies within the margin of the hinge plate. On either side of it 

 and beneath the ligament is a narrow, vertically striated tract. 

 Beneath this again is a slight cardinal rib. Height, 20 mm.; 

 length, 20 mm. 



Hab. — The valve figured was dredged by Mr. J. Brazier in 18 

 fathoms off Ball's Head, Sydney Harbour. Another specimen 

 was taken in 8 fathoms off Nelson's Head, Port Stephens, N.S. W. 



Type to be presented to the Australian Museum. 



The definition of Fischer's section iEquipecten appears to 

 include this species, which more resembles Pecten fasciculatus, 

 Hinds (Reeve, Conch. Icon, viii., PI. xxxv., f. 171), than any 

 figure I can find. 



