476 
restriction of Poll’s genus, as typified by Venus ehione, Linn., will j)rove to be of great 
assistance to all workers. Maorocallista was proposed by Meek to include forms 
resembling Venus gigantea, Gmelin. The shell is transversely elongate-oval, with a 
more or less smooth surface. The pallia! sinus is deep, resembling that of Callista 
proper, but the details of the hinge differ to some extent. 
Maceocallista piaka, Moore, sp., PL 27, figs. 6-8. 
Myacites ‘planus, Moore, Quart. Jouru. Geol. Soc., 1870, xxvi., p. 254, t. 12, t. 10. 
Sp. Char. Shell transversely elongated, somewhat compressed, length about one 
and three-quarters that of the height ; anterior end rounded and narrowed; posterior 
side elongated and pointed ; dorsal margin gently curved posterior to the umbones ; 
ventral margin forming an open free curve ; umbones subcentral, nearer the anterior end ; 
muscular impressions round or oval, usually well marked; pallial sinus very deeply 
indented. Surface nearly smooth, with very fine concentric lines of growth, becoming 
broader towards the ventral margin ; character of the hinge, lunule, and escutcheon not 
ascertained. i 
Ols. I have been unable to satisfactorily refer this shell to any known genus of 
Cretaceous Bivalves, from the obscure preservation of the hinge and teeth. An internal 
cast shows that it possessed both cardinal and lateral teeth, apparently after the type ; 
of the Veneridm, but more than this cannot be said. In outward appearance the shells 
closely resemble those which Mr. Meek has proposed to separate as Maorocallista, but ^ 
the umbones are rather too tumid, and hardly project far enough forward. The species ' 
is not allied to any of those referred to Callista by Stoliezka from the Indian Cretaceous / 
scries. On the other hand, it has much the appearance of a shell called Myacites by 
Mr. E. Etheridge, E.E.S.,* from the Gordon Downs. The shell in question is not a ' . 
Myacites ; it has no characters in common with that genus, and of this Mr. Etheridge \ 
is himself now satisfied. In all probability it is the species under description, and as ; 
to the horizon stated — viz.. Lower Oolite — the beds in which the fossil was found 1 
certainly form a portion of the “ Eolling Downs Eormation.” Eeference may be made ; 
in passing to Myaciies planus, Moore, from Wollumbilla, which presents a resemblance to \ 
our shell, but is perhaps shorter from side to side, the former being longer in proportion 
to its width. The Collection contains other imperfect and unnameable casts which 
may, perhaps, be referable to the present genus, but absolute certainty cannot bo 
affirmed. 
Judging from Moore’s figure, Myacites planus does not appear to be congeneric 
with those on wffiich Schlotheim established the genus Myacites. 
Loc. Walsh Eiver {Mon. A. 0. Gregory) ; Wollumbilla {The late Bev. TV. B. 
Clarice'). 
Eamily — CAEDIIDA2. 
Genus — LEVICABDITIM, Swainson, 1840. 
(Malacology, p. 373.) 
LiEviCAEDiuM Beazieei, sp. nov.\ 
Sp. Char. Shell large, ovate, convex and gibbous, almost equilateral ; test 
thick ; dorsal margin short, curved ; umbones nearly central, gibbous ; anterior and 
posterior ends almost equal, but the latter a little more produced, their margins and 
that of the ventral round, and running into one another ; anterior slope rather flattened, 
* Quart. Journ. Geol. Soc., 1872, xxviii., p. 348. 
t This shell will be figured in a Supplement to the present Work, 
