SILURIAN BIVALVED MOLLUSCA OF VICTORIA. 
Paracyclas siluricus, var. heathcotiensis, nov. Pl. V1., Figs. 
86, 86a. 
Description.—Suborbicular, rounded in front, subtruncate 
behind. Beaks central, salient and subacuminate. sharper than 
in the preceding species. Valves strongly convex, especially in 
the umbonal region, where they become almost ridge-like; super- 
ficial markings in the form of fine concentric striz. 
Measurements.—Length, 13.5 mm.; height, 15.5 mm.; depth 
of valve, 4 mm. 
Observations.—This variety presents marked differences 
from the foregoing species, but in view of the fact that only 
a single example has occurred up to the present, and in associa- 
tion with the specific form, it will be safer for the present to 
regard it merely as a varicty. In common with the type form, 
the figured specimen shows obscure indications of a radial 
lineation of the shell. 
Horizon and Locality—Silurian (Melbournian). Ranges 
east of Heathcote, coll. Geol. Surv., Vict., Bb 50. [988.] 
L 56 | 
