916 MR. G. F. ANGAS ON AUSTRALIAN MOLLUSCA. [Nov. 28, 



liar to Australia. The valves are connected internally by an ossicle 

 in the cartilage, are rough outside, and somewhat pearly within. 

 The left valve is nearly flat and triangular ; whilst the right one is 

 convex, and attached by its front slope to the upper surface of flat 

 sandstone rocks which are laid bare at low water. It occurs near 

 Port-Jackson Heads. I have also procured fine large specimens from 

 Port Lincoln, in South Australia. Length 2^ inches. 



Order VENERACEA. 

 Fam. Mactrid^. 



27. Trigonella contraria. 



Mactra contraria, Desh. P. Z. S. 1854; Reeve, Conch, Icon. 

 Mactra, pi. 17. f. 86. 



Somewhat like M. rufescens. Lam., but flatter and more beaked 

 at the sides, with the umbones smooth, and stained with two violet 

 rays. Rare in Port Jackson. Length 1| inch. 



28. Trigonella luzonica. 



Mactra luzonica, Desh. P. Z. S. 1854; Reeve, Conch. Icon. 

 Mactra, pi. 16. f. 81. 



A neat species, more or less rayed with brown, and tinged with 

 purple at the umbones. Dredged in Middle Harbour on a sandy 

 bottom, also in Botany Bay. Length 1 inch 3 lines. 



29. Trigonella pusilla. 



Mactra pusilla, A. Adams, P. Z. S. 1855, p. 226. 



A pretty, little, shining species, either white or rayed with brown. 

 Dredged in Middle Harbour along with the foregoing. Length 

 7 lines. 



30. *Spisula cretacea. 



Spisula cretacea, Angas, antea, p. 909, PL XLiv. f. 6. 

 A dull-white, chalky-looking shell, not unlike in form to the Bri- 

 tish S. subtruncata. Dredged in Port Stephen. Length 10 lines. 



31. Spisula corbuloides. 



Mactra corbuloides, Desh. P. Z. S. 1854 ; Reeve, pi. 19. f. 103. 



1 Mactra rostrata, Spengler, Skrift. Nat. Selsk. v. p. 115. 



A stout, gibbous, trigonal species, strongly keeled from the um- 

 bones, and covered with a pale greenish-olive epidermis. Dredged 

 in Illawarra Lake. Length 1 1 lines. A dwarf variety is found 

 in Rushcutter's Bay, Port Jackson, and also at Moreton Bay ; it 

 measures 5 lines in length. 



32. *Spisula producta. 



Spisula producta, Angas, antea, p. 909, PI. XLiv. f. 7. 



A small, whitish, triangular, somewhat compressed species, pro- 



