PELECYPODA 167 



Length 2-4 mm. ; height 3 mm. ; thickness (one valve) 07 mm. (Holotype). 



Habitat: Off Three Kings Islands, St. 933, 260 m. 



In addition to the two Recent species of Cratis described above, there are two 

 Australian species; the genotype, progressa, Hedley (1915, Proc. Linn. Soc. N.S.W., 

 xxxix, p. 698), from 100 fathoms, north-east of Port Macquarie, New South Wales, and 

 cuboides (Verco) (1907, Trans. Roy. Soc. S. Australia, xxxi, p. 223), from 20 fathoms, 

 Backstairs Passage, South Australia. 



Family PECTINIDAE 



Genus Cyclopecten, Verrill, 1897 



Subgenus Cyclochlamys, Finlay, 1926 



Type (original designation): Pecten transenna, Suter, 1913 



Cyclopecten (Cyclochlamys) aupouria n.sp. (Plate XLVII, figs. 1, 2). 



Shell minute, white, inequivalve and inequilateral, thin and fragile, with discrepant 

 sculpture on the two valves. Left valve sculptured with thin regularly spaced concentric 

 lamellae and fine interstitial radial threads. The concentric lamellae are about six per 

 millimetre. Ears subequal, small, not distinctly marked off from the disc. Beaks raised 

 in the form of small rounded knobs. Right valve flatter than the left and sculptured 

 with very much finer thread-like concentric lines, about twenty per millimetre, inter- 

 spaces with dense microscopic radials. Anterior ear with five thickened concentric 

 folds, posterior with a well-defined byssal sinus, several indistinct radials and radial 

 crenulations along the hinge margin. Interior smooth, hinge line straight with a 

 minute triangular resilium. 



Diameter: antero-posterior 3-4 mm., dorso-ventral 2-9 mm. ; thickness o-6 mm. 

 (Holotype, left valve). 



Habitat: Off Three Kings Islands, St. 933, 260 m. 



Cyclopecten (Cyclochlamys) secundus, Finlay, 1926. 



1919. Pecten aff. transenna, Mestayer, Trans. N.Z. Inst., LI, p. 135, pi. 8, fig. 11. 

 1926. Cyclochlamys secundus, Finlay, Trans. N.Z. Inst., lvii, p. 453. 



A figure is provided (Plate XLVII, fig. 3) of what appears to be the right valve of 

 secundus. It is delicately sculptured with extremely dense concentric threads chopped 

 up into numerous radial series but with no raised radials showing. The whole effect is 

 an intricate tessellated pattern caused by alternating sections of the concentric ribbing 

 varying in spacing. 



Diameter: antero-posterior 2-8 mm.; dorso-ventral 2-4 mm. 



Habitat: Off Three Kings Islands, St. 933, 260 m. 



Finlay described his Cyclochlamys (loc. cit., 1926, p. 452) as having both right and 

 left valves nodulous but Marwick (1928, Trans. N.Z. Inst., lviii, p. 453) has shown that 

 the right valve is almost smooth as in true Cyclopecten. It will be necessary to compare 

 the genotypes before the status of Cyclochlamys can be determined. 



