SILURIAN BIVALYED MOLLUSCA OF VICTORIA. 
Ludlow of Benson Knot, Kendal, Westmoreland. The charac- 
ters which separate our species from McCoy’s are the depressed 
umbones and the more closely striated surface in the former. 
In common with the Ludlow species, the specimens from Heath- 
cote also show the same variation in the length of the shell; our 
figured type being a rather elongate form. 
Horizon and Locality. — Silurian (Melbournian). Ranges 
east of Heathcote. Coll, of the Geol. Surv. Viet., B b - 50 
1 987, type]. Also specimens from the same locality presented 
to the Museum by Mr. J. IT. Gatliff. 
Genus Palceanatina, J. Hall, 1870. 
Palceanatina cf. solenoides, J. Hall. PI. I., Pig. 6. 
Palceanatina solenoides, J. Hall, 1885, Pal. N.Y., Vol. V., 
Pt. I., Lamell. II., p. 489, PI. LXXIX., Pigs. 38, 39. 
Observations. — The specimen before us is unfortunately in- 
complete, but there is enough evidence to show that it was thin- 
shelled, inequivalve, the left valve larger than the right. It 
bears a fairly close resemblance to the comparatively large, 
parallel-sided species from the Devonian of N. America, quoted 
above. 
Horizon and Locality. — Silurian (Melbournian). In hard, 
grey mudstone, S. Yarra. Presented to the National Museum 
by Mr. A. E. Kitson, P.G.S. [7875.] 
Genus Ebmondia, de Koninck, 1842. 
Edmondia perobliqua, sp. nov., PI. I., Pigs. 7, 8; PI. I., Pig. 9. 
Description. — Shell sub-ovate, oblique; thickest in the 
median and umbonal area. Beaks rather inflated, directed 
forward, and situated anteriorly. Anterior border short, and 
truncated towards the ventral margin, curving widely to the 
posterior extremity, where it turns abruptly upwards to meet 
the cardinal line. Cardinal border moderately short. In the 
cast of the shell there is a depression beneath the posterior 
umbonal slope indicating a ridge or support inside the shell, 
terminating in a semilunar muscle scar. The posterior area of 
the shell is compressed, and almost nasute at the postero-ventral 
margin; and sometimes it is expanded, as in Ptychodesma, J. 
Hall, to which this form shows certain affinities. Surface of 
shell with fine concentric lines of growth, and obscure radii, 
especially noticeable on the umbonal slope. 
The shell of this species was evidently very thin, since the 
sculpturing is conspicuous on the casts. 
[ 38 1 
