MCORE—AUSIRALIAN MESOZOIC GHOLOGY, 245 
shell ; its chief peculiarity appears to be its very high and conical 
figure in proportion to its size. 
It is from Wollumbilla. F 
9. RHYNCHONELLA RUSTICA, sp.n. Pl. X. figs. 7-9. 
Shell variable, usually wider than long ; beak acute ; when young, 
compressed, with both valves slightly convex, without sinus, and 
margins rounded; with age, the shell is furnished with a broad 
sinus in the ventral, with a corresponding convexity or mesial 
fold in the dorsal valve; surface covered with stria, from 20 to 
25 in number, which in the adult shell are somewhat wavy or ir- 
regular. 
With age the dorsal valve becomes very convex, and the frontal 
margin considerably thickened. It approaches most closely to the 
Kh. concinna of the Great Oolite and Bradford Clay; but in its ge- 
neral aspect it is a coarser shell, and the plice are more irregular. 
I have seen about twenty examples, so that it must be very abun- 
dant. In the hollows of the strive are occasionally Polyzoa, and 
attached Foraminifera. 
It is from the Wollumbilla district. 
10. RayncHonELLA soLivaRtaA,n. sp. Pl. X. fig. 10. 
Shell wider than long; ventral valve with broad mesial sinus, in 
which are four widely spreading costs, with a single lateral costa 
on either side of the sinus. ‘Towards the umbo the shell is smooth, 
and without appearance of coste. 
Only a single specimen of a ventral valve of this species occurs, in 
one of the Wollumbilla blocks; and this is not quite perfect. 
11. Terepraterta Davinsonu, sp.n. Pl. X. figs. 1 & 2. 
Shell rather large, transversely ovate or subtrigonal, slightly con- 
vex; beak truncated ; ventral area extended and slightly depressed 
below a lengthened, slightly rounded hinge-line. The surface of the 
valves exhibits distinct but very minute punctations, and possesses 
wide concentric bands, on which are regular, but much finer, lines 
of growth ; these are crossed by numerous radiating strie, which, 
towards the margins of the folds, give the shell a fimbriated appear- 
ance, very fine plice being visible on the whole of the surface. The 
larger or dorsal valve possesses a wide mesial fold, with a correspond- 
ing sinus on the ventral valve. 
Three examples of this very pretty species occur, but only one is 
free from the matrix and tolerably perfect. 
From the Wollumbilla drift-boulders. 
12. Avicuta Barxtryi, sp. n. Pl. XI. figs. 1 & 2. 
Shell slightly inequilateral, orbicular; large valve convex, small 
valve flattened, umbones prominent; auricles rather small, nearly 
equal. 
The large valve is slightly produced posteriorly, and is ornamented 
by about 24 radiating cost, which are more raised and appear 
