174 



Locality. — Upper beds at Muddy Creek. 



This Thracia-like species is very similar to and has the same 

 interior characters as Alicia angustata, Angas, but is more 

 robust and broader. 



Myodora angustior, spec. nov. Plate xvi., fig. 16. 



This species is related to the last, but is less inequilateral, 

 and is much narrower than the allied species M. angustata; the 

 concentric ridges are more pronounced, and the post-umbonal 

 angulation is almost obsolete. The pallial sinus, which is 

 strap-shaped, extends across to the anterior adductor scar as in 

 Alicia elegantula, Angas ; but the shape of that species is very 

 different. 



Dimensions. — Antero-posterior diameter, 10 ; umbo-ventral 

 diameter, 4'5 millimetres. 



Locality. — Upper beds at Muddy Creek. 



Myodora tenuilirata, spec, nov Plate xvii., figs. 9a — 9&. 



Transversely elongate-oblong, thin, inequilateral, somewhat 

 acuminately rounded in front, abruptly truncated behind. 

 Bight valve moderately convex ; post-dorsal margin nearly 

 straight, much longer than the front-dorsal margin, which 

 makes with it an angle of about 150 deg. ; posterior margin ver- 

 tically truncated ; ventral margin very gently curved, except 

 towards the anterior, where it rapidly ascends. Conspicuously 

 carinated from the umbo to the post-ventral angle. Surface 

 ornamented with close-set, fine, concentric ridges, crossed by 

 radial wavy microscopic thread-like lines. Left valve flat, a 

 little concave in the umbonal region, with a few concentric 

 lines, but the radiating minute threads more conspicuous and 

 crowded than on the other valve. 



Dimensions. — Antero-posterior diameter, 16 ; umbo-ventral 

 diameter, 10 ; sectional diameter of both valves, 3 millimetres. 



Localities. — Victoria : lower beds at Muddy Creek ; Corio 

 Bay; Schnapper Point. S. Australia: Turitella grits at 

 Ardrossan ; oyster beds of the Biver Murray Cliffs at Nor'- 

 "West Bend ; gastropod beds near Morgan. 



Among living species M. tenuilirata has a general resem- 

 blance to M. pandorceformis, Stutchbury, but it differs from it 

 by being less convex, more produced posteriorly, its post- 

 dorsal margin straighter, its ventral margin less arched, and 

 by its more numerous concentric ribs. The fossil congener, 

 M. australis, is easily separable from it by its shape. 



Myodora australis, Johnston. Plate xvii., figs. 10a — 10&. 

 Reference— Proc. Boy. Soc, Tasm., for 1879, p. 40. 

 Ovately-oblong, inequilateral, thick, anterior side the 



