246 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. 
spinous on the posterior margin. The small valve is but very slightly 
convex, and is very distinct in its ornamentation from the larger, 
the costs being much finer and about 44innumber. The cost are 
decussated by numerous regular concentric lines of growth, which, 
when they meet, give them anodulated aspect. The lines of growth 
have been refiected or folded over the anterior auricle and side, which 
gives the shell a very peculiar appearance. ‘The small valve possesses 
a large and deep groove for the passage of a byssus. 
The punetate structure of the Aviculide may be clearly distin- 
guished, by aid of the lens, in this species. Sections of the shells of 
this genus are to be seen in almost every block from Wollumbilla ; 
but the above is the only specimen clear of the matrix. It is 
from Wollumbilla, and is named after Sir Henry Barkly, late Go- 
yernor of Victoria. 
13. AviIcULA REFLECTA, sp.n. Pl. XII. fig. 1. 
Shell rather inequivalve, rather longer than wide; large valve re- 
gularly convex; surface ornamented by about 38 radiating and 
slightly undulating costs, every fourth costa being rather more pro- 
minent, which are crossed by widely separated interrupted lines of 
growth. The surface is also decussated by thin bands of con- 
centric strie, which terminate with a slightly fimbriated or ragged 
edge. 
On the back of this specimen, covering the auricles and the umbo, 
a small valve is attached, which probably belongs to it. In its 
general contour it resembles A. Barklyi; but the longitudinal 
coste are finer and in greater number, being as 57 to 44 in the 
latter ; these are decussated, as on the larger valve, by very thin 
wayy concentric stric. 
Numerous examples of Planorbulina Ungeriana are attached to 
the small yalve; and a Watica, with a Zima and fragments of other 
Aviculide, are in the same block. 
Loc. Wollumbilla. 
14. AviovLA umBoNALIS, sp.n. Pl. XII. figs. 2 & 3. 
Shell thick, transversely ovate; umbo produced and sharply in- 
curved over small valve; hinge-line extended and nearly equal on 
both anterior and posterior sides; large valve convex, small valve 
flattened, both of which have longitudinal striz and narrow wavy 
lines of growth. 
This species is represented by a single specimen, the test of which 
is imperfect. Its peculiar hinge-line clearly separates it from either 
of the other Australian species; and its shell, unlike that of the Ayi- 
culidee, is comparatively very thick. 
Loc. Wollumbilla. 
15. AvicuLA coRBIENSIS, sp.n. Pl. XI. fig. 7. 
Sheli longitudinally ovate, longer than wide, nearly equilateral ; 
umbo distinct, raised, curving over hinge-line; posterior auricle 
short, anterior obsolete ; anterior margin and front regularly round- 
