314 



THETIS SCIENTIFIC RESULTS. 



0h 



Ur 



CRASS ATELLITES SCABRILIRATA, sp. nov. 



(Fig. 54.) 



Station 13. 



Shell small, rather thin and flattened, rhomboidal, very inequi- 

 lateral, the posterior side twice the length of the anterior. 



Colour dull pale yellow. Sculp- 

 ture about ten low, broad, 

 downwardly curved lamellae, 

 which are radiately transversed 

 by rows of microscopic scales. 

 Lunule and dorsal area elon- 

 gate and narrow. Umbo acute. 

 Inner ventral margin smooth. 

 Length, 6-7 ; height, 4-8 mm. 

 Its peculiar microscopic sculp- 

 ture distinguishes this from all 

 southern forms, but connects 

 it with C. rhomhoides. Smith, 

 a species originally described 

 '. have taken in 15 fathoms off 

 not so abruptly truncated 



CRASSATELLITES SCABRILIRATA. 



Fig. 54. 

 from Torres Straits, but which 

 Palm Islands. G. scahrilirata 



anteriorly, nor so flattened, and has fewer and broader concentric 

 ribs than C. rhomhoides. 



One half -grown valve was taken off Cape Three Points in 41-50 

 fathoms. T have drawn the figure and description from better 

 material taken off Port Stephens by a Museum dredging excursion. 



C U N A, gen. nov. 



A genus of the CrassateJIitidce. Shell very small, equilateral or 

 slightly rostrate, higher than long, with lunule and impressed 

 dorsal area, beaks erect, prodissoconch marked, valves sometimes 

 clasping. Sculpture radiate or concentric, or both. Inner ventral 

 margin usually denticulate. Hinge plate broad and flat ; in the 

 left valve two well developed cardinals ; in the right a rudimen- 

 tar}' cai'dinal and a massive, projecting, flat-topped and triangular 

 cardinal. Laterals produced, sometimes transversely striated, a 

 posterior and anterior in each valve. Ligament partly internal, 

 protruding in a notch below the beaks. 



Type C'una cuncentrica, Hedley. 



This genus, which embraces Kellia atkinsoni, Ten. Woods, 

 Carditdia delta, Tate and May, ifec, has hitherto been confounded 

 with Carditelia, the hinge structure of which is of a difierent 

 plan. The erect beak and the fissure above the chondrophore 

 readily distinguish Cuna from Carditelia. The late Prof. Tate 

 told me that species like his C delta occurred fossil in the Aus- 

 tralian Tertiary. 



