SMIXn : ON AUSTKALIAN MACTRID^. 139 



practically without any sinus, a feature which distinguishes it from 

 the other small species of Mactridse from the Australian coast. 



The lateral teeth are long, and smooth within and without, but 

 the single tooth on each side in the left valve is roughened or 

 microscopically granuhir on the edge. There is a single solid 

 triangular A-shaped cardinal tooth in this valve, in front of the 

 resilium pit, and a minute denticle above the point of the A. A 

 similar A tooth is in the riglit valve, the posterior phlange of the 



A forming the boundary of tlie resilium pit. The triangular resilium 

 reaches to the umbones, causing a slight break in the dorsal margin. 

 The external ligament is feeble, thin, marginal, and scarcely anything 

 more than a hair-like line. 



Tate (Trans. R. Soc. S. Aust., vol. ix, p. 84, 1887) united this 

 species with J/, ovalina, Lamarck, but that form is a very different 

 sliell according to Delessert's figure. 



4. Macira (Standella) .sigtptiaca, Chemnitz. B.M. 



Mactra tegyptiaca, Chemnitz, Conch. Cab., vol. xi, p. 218, pi. 200, 



figs. 1955-6; Dillwyn, Cat., p. 145 ; lleeve, pi. xx, fig. 112. 

 Spistila (cgyptiaca, Gray, Mag. Nat. Hist., i, p. 373, 1837. 

 Merope cegyptiaca, Angas, Proc. Zool. Soc, 1871, p. 100. 



Hah. — Port Essington and Port Curtis (Brit. Mus.), North Australia 

 (Mrs. Ince in Brit. Mus.), Bed Sea (Chemnitz), Ceylon (Reeve), Lake 

 Macquarie, New South AVales (Angas), whole of Queensland coast 

 (Hedley). 



The Port Essington specimens were collected by Mr. John Gouhl, 

 the ornithologist, and J. McGillivray, and consequently the locality 

 may be relied upon as coiTect. This species may be, as suggested by 

 some authors, the M. nicoharica of Gmelin, founded on a figure in 

 Chemnitz (vol. vi, pi. xxiv, fig. 237). 



5. Mactra alta, Deshayes. B.M. 



Mactra alta, Deshayes, Proc. Zool. Soc, 1854, p. 347; Weinkauff, 

 p. 113. 



Hab. — North-east coast of Australia (Brit. Mus.), Australia 

 (Weinkauff and Deshayes). 



Length 70, height 63, diam. 39 mm. 



Allied to M. abbreviata, but differing somewhat in form, being 

 more equilateral, less produced posteriorly, and higher in proportion 



VOL. XI.— JUNE, 1914. 10 



