SILURIAN BIVALVED MOLLUSCA OF VICTORIA. 
Affinities. — This type of shell belongs to the group exempli- 
fied by Grammysia subarcuata, J. Hall,* from the Chemung 
Group of N. America, especially in having a forwardly pro- 
jecting beak with the ventral border narrowing anteriorly. 
Another form also distinctly related, is the Myacites striatulus 
of Romer,t which notably differs in its more depressed beak. 
Observations. — It is interesting to record that McCoy, who 
established this genus, selected the specimen now figured, as an 
example of Leptodomus ; it was, however, not specifically de- 
termined. This is probably the same form to which McCoy 
referred in a note on \ sheet, 4 S.W. Geol. Surv. of Victoria, 
as “ Leptodomus allied to aviygdalinus. ,, \ The species named 
may be allied to Hall’s genus Pholadella. 
It is appropriate to dedicate this species to one who did 
such signal work in describing many typical genera and species 
of British palaeozoic mollnsca. 
Horizon and Locality. — Silurian (Melbournian). Type 
specimen [976] from Broadhurst’s Creek, east of Kilmore, Geol. 
Surv., Viet., B b 18; north-east of Kilmore, Geol. Surv., Viet., B b 
24. Also west of Mount Disappointment, gully near porphyritic 
dyke, Geol. Surv. Viet., B b - 16. 
Leptodomus heathcotiensis, sp. nov. PI. I., Fig. 5. 
Description. — Shell subtrigonal, elongate, compressed; 
rounded in front, subtruncated behind; ventral margin more or 
less parallel with the cardinal border, but slightly incurved, 
owing to a feeble sinus extending in a vertical line from the 
beaks to the ventral margin. Beaks anterior, salient, and nearly 
terminal. Cardinal line straight. Posterior cardinal area 
hollowed from the beaks to the postero-ventral margin, resulting 
in a curved umbonal ridge below. Median area depressed. 
Surface having numerous parallel concentric ridges (about 18 
to 20). 
Measurements. — Type specimen : Length, 25 mm. ; height, 
about 13 mm.; depth of left valve, 4 mm. 
Affinities. — The nearest allied form with ours is un- 
doubtedly McCoy’s “leptodomus truncatus”§ from the Upper 
* Preliminary notice, Lamellibrancliiata, 2, 1870, p. 61 : G. (Leptodomus?) subarcuata, 
J. Hall, Pal. N.Y., Vol. V., Pt. I., 1885, Lamell., II., p. 375, PI. LXI., Figs. 10-22; PI. 
XCIIL, Fig. 26. 
t Das Rheinische Uebergangsgebirge, 1S44, P- 7 9> FI. II., Fig. 5, Also Beushausen, 
Abhandl. Kon. Preuss. Geol. Landesanst, N.F. Heft, XVII., 1895, p. 265, PI. XXIV., 
Fi" S . 12-14* 
0 + See Sowerby, in Murchison’s Silurian System, 1839, P- 609, P! - v -> Fig. 2—“ Cyfn- 
cardia amygdalinar’ 
§ British Palaeozoic Fossils, Pt. II., 1852, p. 279, PI. ik., Pigs. 21-24. 
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6608 .— B. 
