t.he surface of the valves being only partially, instead of wholly 
radiate, but the deltoid outline, truncate anterior end, and elevated 
beaks are very characteristic features of all three genera and the 
present species. 
In dealing with the mollusca of a comparatively new region, 
and an almost unworked horizon, it is difficult to adopt many 
known genera, on imperfect and incomplete materials, and it is 
possible, therefore, that A*1 poststriata may represent an undescribed 
and peculiarly Australian genus. 
When the shell is viewed looking at the anterior end, the latter 
is seen to be flattened, or as I have described it above, straight- 
walled, and the byssal opening to be large and somewhat cordate. 
The form of this opening is quite in keeping with the structure of 
Ambony chia, an excellent figure being given by Hall in his 
“ Supplementary note on the Genus Ambonychia,”* which exem- 
plifies it. The figured valve of A. % poststriata , the left one, is 
three and three-quarter inches long, by three inches high, and with 
a diagonal measurement of three and three-quarter inches. The 
concentric sculpture of our species is similar to that of Ambony chia? 
triton , Salter,f and so is the outline, but the posterior slope of the 
latter is not radiate. 
Prof. Tate writes me that he possesses an Ambonychia-like shell 
from Lilydale, with fenestrated ornament. It can hardly be A.? 
poststriata , which is fenestrate only on the posterior slope. He 
also informs me that the Rev. Mr. Cresswell gave him a small, 
neat Conocardium from the same locality. 
Class GASTEROPODA. 
Order PROSOBRANCHIATA. 
Family Littorinid;e. 
Genus Cyclonema, Hall , 1852. 
(Pal. N. York, II., p. 89.) 
Cyclonema australis, Eth.fil. 
(PI. xix., figs. 1 and 2.) 
C. ? australis , Eth. til., Records Austr. Mus., 1890, I., pt. iii., p. 
63, t. xix., f. 4 and 5. 
Obs . — I take this opportunity of figuring a far better specimen 
of this species than I was formerly able to do. From it the 
following characters are deduceable. The whorls are six in num- 
ber, the body whorl being somewhat inflated. The spiral ridges 
in this particular specimen are alternately larger and smaller, and 
* Pal. N. York, III., pt. i., p. 523, f. 2. 
f Mem. Geol. Survey Gt. Brit., II., pt. i., t. 23, f. 5. 
