144 



Cucullsea Corioensis, McCoy. 



Beference. — Prodr. Pal., Victoria, Dec. Ill , t. 27, figs. 3-5, 

 1876. 



Localities. — Victoria: common at most of the localities ; 

 Corio Bay; Bird Eock Point ; Point Addis ; Gellibrand Eiver ; 

 Muddy Creek ! ; Mordialloc ; Dog Island, Leigh Eiver ; 

 Bairnsdale ; Jemmy's Pomt, Grippsland Lakes ; Schnapper 

 Point {McCoy). 



Tasmania : Table Cape ! {B. 31. Johnston) . 



South Australia : very common in the calciferous sandrock 

 of the E. Murray Cliffs, near Morgan ; in a well-sinking at the 

 Nine-mile Camp, near Morgan ; casts in the hard calciferous 

 sandstones associated with the oyster banks at Aldinga and 

 Adelaide (B.T.) 



Cucullsea Adelaidensis, sijec. nov. PL xi., fig. 14. 



Shell obliquely trapezoidal, very tumid, inequilateral ; um- 

 bones large, incurved, slightly in front ; anterior margin 

 rounded, ventral margin straight, oblique to the straight hinge 

 line ; posterior margin slightly undulating, obtusely truncated ; 

 posterior slope flattened, separated from the moderately convex 

 rest of the valve by an obtusely rounded ridge extending from 

 the umbo to the post-ventral margin. Surface oruamented 

 with fine, narrow, radial riblets, not much wider than the im- 

 pressed furrows, crossed by numerous close-set retroflexed 

 lamiuse of growth. In the umbonal region the transverse 

 laminsB are wider apart, and at the intersections form granula- 

 tions, but towards the front they are more crowded, and are 

 raised on the riblets into squamae. The radial riblets increase 

 by bifurcation, and at the proximal end the duplication is indi- 

 cated by a linear sulcus. Inner margin of the valves coarsely 

 ridged. ^ The ligamental area is marked with five impressed 

 divaricating furrows. There are three or four anterior and four 

 or five posterior longitudinal laminar teeth. The central teeth 

 are small and transverse, and increase in size and obliquity 

 outwards. The post-adductor muscular impression with a 

 thickened, but not elevated, inner margin. 



Dimensions of an average-sized specimen : — Length from 

 antero-dorsal to post- ventral margin, 4.4 ; width from umbo to 

 ventral margin, 29 ; thickness through both valves, 30. 



Locality. — Many specimeus obtained from the glauconitic 

 sands, Adelaide bore. 



This species closely resembles C. Corioensis, but may at a 

 glance be distinguished by its more oblique outline and finer 

 sculpture ; also it is less tumid, the umboces not so wide, and 

 the radial ribs are narrower and more numerous. 



