SILURIAN BIVALVED MOLLUSCA OF VICTORIA. 
(Ee,). Although we have only a mould from a single specimen 
to judge by, there can be no hesitation in assigning our example 
to the above species, for it shows the following characters in 
common with Barrande’s figured specimens : —Shell longer than 
high, sub-oval, truncately rounded in front at the base, boldly 
curved behind; beaks low, pointed slightly forward, and situated 
anteriorly. The riblets are numerous (usually about 80), 
rounded; moderately strong on the basal margin, becoming very 
fine and almost obsolete towards the umbo. The shell-surface 
is marked with concentric, inequidistant furrows. 
The hinge characters are not shown in any of Barrande’s 
specimens, nor in ours, but in the latter the area on either side 
of the beaks is marked with several conspicuous short, curved 
folds or ligamental grooves, more or less parallel with the car- 
dinal border. 
Compared with actual Silurian (Stage E in the Bohemian 
Basin) species of the genus, our specimen difiers from the 
nearest allied form, P. dustralis* in its more sharply truncated 
anterior, and higher shell. 
Horizon and Locality.—Silurian (Yeringian). Maindample, 
near Mansfield. Presented by Mr. Hutchinson, per Rev. R. 
Thom. [7882. | 
Family Ctenodontide. 
Genus CTENODONTA, Salter, 1851. 
It seems convenient to refer the nuculoid shells without 
ligament-pit (resilifer) to Salter’s genus, whilst the subrostrate 
forms of the same type find a place in Palwoneilo of J. Hall. 
Some authors, as Beushausen, include both the above-named 
forms in the one genus. 
Ctenodonta portlocki, sp. nov., Pl. Il. Figs. 17-20. 
Description.—Outline of shell variably elongate-ovate to 
subquadrate; with moderately high umbones and a prominent 
cardinal area, the hinge lines sloping away from the umbo. 
Beaks anterior, the posterior hinge line twice the length of the 
anterior. Surface of shell concentrically striate, or with shal- 
low concentric grooves. 
* Barrande, op. cit., Pl. LXXI., Figs. 1-13. 
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