SILURIAN BIVALVED MOLLUSCA OF VICTORIA. 
Ornamented with concentric rings of growth, appearing as 
irregular folds, and most strongly marked near the extremities. 
All the examples known at present from Victoria are in the 
form of sandstone casts, so that the finer markings, if any, have 
perchance been lost. In wax squeezes taken from these casts 
there seem to be faint traces of a feeble radial, linear sculptur- 
ing, such as is seen in Paracyclas lineata, Goldfuss sp.*, which, 
by the way, our species otherwise resembles, with the exception 
that the latter is more regularly convex over the whole surface. 
Measurements.—Figured specimen: Length, 15.5 mm.; 
height, 15.5 mm.; depth of valve, 3.5 mm. 
Observations.—The present species resembles McCoy's 
Anodontopsis bullat in its general shape, but differs in the 
coarser sculpturing of the shell-surface. The 4. bulla, McCoy, 
does not appear to show any decided affinities with the other 
species described under the generic name Anodontopsis by 
McCoy, and seems to be a typical example of the earlier 
described genus Paracyclas. 
It is of much interest to record that McCoy indicated the 
actual specimens with which I am now dealing as “a new form 
of Anodontopsis allied to A. bulla,” by a pencil note written on 
the tablet of a mounted series in the Museum. The generic 
name Anodontopsis, besides being ante-dated by Paracyclas, 
appears to embrace three generic types as exemplified by 
McCoy’s published species in his “British Paleozoic Fossils,” 
as follow :— 
Anodontopsis bulla, McCoy = Paracyclas, J. Hall, 1845. 
A. angustifrons, McCoy = Modiomorpha, J. Hall, 1870. 
A. quadratus, McCoy =Cypricardella, J. Hall, 1856 
(Microdon, Conrad, 1842—pre-occupied by Agassiz’s genus). 
Another species which may be cited for comparison with 
ours is Paracyclas elliptica, J. Hall,t from the Corniferous 
Limestone and the Hamilton Group of the United States and 
Sanada. It is, however, not so high, and the lire are more 
distinct and more closely set. 
Horizon and Locality—Silurian (Melbournian). — Coll. 
Geol. Surv., Moonee Ponds Creek, Flemington. Ranges east of 
Heathcote, B> 50, very common. [7947 (type), 7948.) 
*Petrefactia Germania, 1834-40, p. 227, Pl. CXLVI., Figs. 8a, 3d. 
+ Lucina bulla, McCoy sp., Syn. Silur. Foss., Ireland, 1846, p. 17, Pl. IL., Fig. 1. 
Anodontopsis bulla, McCoy, 1852, Brit. Pal. Foss., Pt. II., p. 271, Pl. 1K., Figs. 11-13. 
*Pal. N. York, Vol. V., Pt. I., 1885, Lamell. II., p. 440, Pl. LXXII., Figs. 23-33; 
P}. XCV., Fig. 18. 
