163 



tusely angled from the umbo to the post-ventral border ; ven- 

 tral and post-dorsal margins straight, almost parallel. Umbo 

 conspicuous, incurved ; lunule small, but well denned. 



Surface with somewhat distant and irregularly disposed con- 

 centric lamella?, slightly crenated and foliated, especially on 

 the posterior slope, and rayed with rather distant flat ribs, 

 equal in width to the interspaces. Hinge of right valve with 

 three cardinal teeth, widely and equally separated ; the an- 

 terior one short and stout, the others very prominent and 

 simple ; the ligamental lamella extends to more than half the 

 length of the post-dorsal line. Pallial sinus small, rounded, 

 horizontal. 



Dimensions. — Length, 12 ; height, 7 ; thickness through both 

 valves, 5 millimetres. 



Localities. — Upper beds at Muddy Creek, Hamilton ; and 

 oyster beds of the Eiver Murray Cliffs at the Nor'-AVest 

 Bend. 



This species has a great resemblance to V. exotica, Lamarck, 

 but the umbo is larger and more cordate ; the posterior margin 

 is narrower, the post-dorsal area is more defined, and the radial 

 ribs are flat, and not angular ; internally further differences 

 are presented by the cardinal teeth and the elongate ligamen- 

 tal lamella. In its flat ribs and cordate umbo, the fossil re- 

 sembles V. mitis, Desh., but is in other respects different. 



Gents Tellina. 



synopsis of species. 



Siphonal inflection confounded with the pallial line. 

 Elongate, hardly compressed, posteriorly subrostrated. 



T. lata. 

 Oval, compressed, posteriorly sub-angular. 



T. albineUoides. 



Oblong, posteriorly short and cuneiform. Umbo in 



posterior one-fourth ; ventral margin nearly straight. 



T. jjorrecta. 



Umbo in posterior one-third ; ventral margin arched ; 



lamellate T. Masoni. 



Triangularly-ovate, compressed, posteriorly flexuous and 



obsoletely carinated T. Cainozoica. 



Siphonal inflection detached from the pallial line. 



Oval-oblong, nearly equilateral ; somewhat smooth. 



T. equilatera. 

 Elongate oval ; inequilateral ; concentrically ridged. 



T. Stirlincfi. 



