130 



semblance to some species of Yoldia ; it, however, does not 

 belong to that genus, as the valves are closed, and the pallial 

 sinus is small. It recalls some of the Jurassic species, notably 

 i. suhovalis, Goldfuss, of the European Lias. 



Leda planiuscula, spec. nov. PL v., fig. 2. 



Shell minute, similar to L. oholella : comparing equal-sized 

 specimens of each, L. planiuscula is more depressed, and the 

 outline approaches more to the circular. 



Dimensions. — Length, 5 ; height, 4'5 millimetres. 



Locality, — Adelaide bore. 



Leda Huttoni Tenison-Woods. PI. vi., fig. 4. 



Reference.— Vvoc.Jjimi. Soc, N.S.W., vol.iii., p. 239, tab. 21, 

 fig. 2, 1878. 



Shell small, depressed, thin, fragile, shining, transversely 

 elongate, pyriform, concentrically irregularly striate and 

 broadly sulcate, radially finely striated ; posterior side much 

 produced and slightly obliquely truncated at the end ; obtusely 

 triangulated. Anterior side short, rounded. Cardinal teeth 

 numerous, minutely angular. 



Dimensions. — Length, 11 ; height, 5 millimetres. 



Localities. — Muddy Creek, Hamilton, where it is common ! ; 

 Table Cape ! ; Adelaide bore ; and Turritella clays, Aldinga 

 {B.T.). 



The specimens from Adelaide and Aldinga are a little more 

 inflated, and the anterior side shorter, whilst the post-dorsal 

 margin is sloping and not elevated at the end ; the arched 

 rostral prolongation is very conspicuous in young shells from 

 Muddy Creek, but the character is not constant. 



Leda acinaciformis, spec. nov. PI. v., figs. 6a— 66. 



Shell depressed, elongate-oval ; umbo subcentral ; anterior 

 side rounded ; dorsal margin sloping anteriorly, and slightly 

 elevated at the posterior end ; ventral margin strongly arcuate, 

 curved upwards posteriorly to form a rostral prolongation. 

 TJmbonal ridge well defined, above which is a narrow lanceo- 

 late area. Surface sculptured with concentric, thick, flattened 

 ribs. The regular convexity of the anterior surface is inter- 

 rupted by a narrow, flattened, triangular area extending from 

 the umbo to the antero-ventral margin, rendered conspicuous 

 by the interrupted curve of the concentric ribs. Lunule lan- 

 ceolate, longitudinally ridged. 



Dimensions. — Length, 17 ; height, 8 ; thickness through both 

 valves, 6 millimetres. 



Locality. — Muddy Creek. 



L. acinaciformis ^has the general form and ornament of 



