473 
Ols. It was not until I liad examined Prof. Tate’s Collection of Soutli Australian 
Cretaceous fossils that I was able to make out the generic relations of this species, 
through a knowledge of the internal hinge characters, having previously referred the 
type (PI. 27, figs. 2 and 3) to the genus Mactra. 
In the left valve of Z7. Meeki the conical cardinal tooth is well marked and 
prominent, with a deep socket on its posterior side for the reception of the tooth of the 
right valve. 
Unicardium cardioideum, Phillips,'* has similar wide concentric lines of growth to 
the present species. 
In a future publication the hinge structure of this species will be figured. 
Loo. Walsh River {Hon. A. O. 0-regory) . 
Order-YEISERACEA. 
Pamily— VETSTERID^. 
Oenus — CYTHLIIL! A, Lamarck, 1806. 
(Ann. Mus. Hist. Nat. Paris, vii., p. 132.) 
CXTHEEEA ‘WOODWAKDIA-N-A, JIudleston, PI. 27, figS. 12-14. 
Cytkerea Woodwardiana, Hudleston, Geol. Mag., 1884, i., p, 340, t. 11, f. Sa-D. 
Sp. Char. Shell ov-al, compressed, veneriform, longer than broad. Hinge-line 
inclined on both sides ; dentition unknown j umbones small, quite approximate ; lunule 
almost imperceptible, nearly flat; ligament small, but prominent. Ventral margin 
regularly rounded. Anterior end small, the margin gracefully rounded; posterior end 
rather more produced than the anterior. Pallial sinus large, and much sinuated for so 
small a shell, the first turn from the anterior towards the posterior end, forming a very 
sharj) angle. Surface with about five broad, concentric, flat undulations, between which 
are very fine close stri®, having a similar direction, and the whole crossed by fine 
radiating strise. 
Ohs. I cannot agree with Mr. W. H. Hudleston in saying that the radiating 
striae are irregular. Oji the examples examiired these linos were quite normal. This 
character and the compressed nature of the valves are excellent features for the 
determination of the species. On removal of the outer shelly layer, the radiating striae, 
it is true, quite disappear. 
The inflection of the hinge calls to mind the structure of the genera Cxjprimeria 
and Oaryatis, rather than that of a true Gytherea, especially such species as Gyprimeria 
gaultina, Loriol.f 
CiTnEEEA ? Hudlestoni, sp. nov., PI. 28, fig. 12. 
Sp. Gliar. Shell ovately trigonal, rather acuminate towards the umbones, tumid ; 
tody of the shell convex, which is more or less maintained to the ventral margin, not 
thinning away rapidly to the latter ; hinge margin much arched ; ventral margin 
rounded ; posterior margin slightly angulated ; posterior slope broad and rounded ; 
surface with regular, concentric, sub-imbricating laminae. 
Ohs. A very obseiire shell, not easily defined, but important as forming con- 
siderable rock masses, associated with Actceon depressus, Moore?, Gucullaa LLendersoni 
(mihi), Lentalmm, aud other shells. 
The nature of the hinge is unknown, and the shell does not possess any very 
distinctive characters beyond its shape. It is an undoubted specific addition to the 
* 111. Geol. York., 3rd Edit., Part i., 1875, t. U, f. 12. 
t Mem. Soo. Pal. Suisse, x., p. 35, t. 7, f. 1-5. 
