Tertiary. ] PALZONTOLOGY OF VICTORIA. [Mollusca, 
ridges simple or branching, arching outwards from the two main ridges of the 
middle division, arising at successive distances so that those nearer the middle are 
shorter than the outer ones (contrary to the usual rule). Entering valve with a 
mesial division extending from the beak to corresponding portion of front margin not 
more convex nor conspicuously raised than the adjacent portions of the moderately 
convex sides, from which it is separated by a conspicuous angular smooth space 
reaching to the angular sinus on each side of the front margin ; usually three simple 
ribs and often a fourth shorter branch on the middle ridge, and five to eight simple 
or rarely branched ribs extending obliquely to the lateral margins at an acute angle, 
from the sides of the middle area, so that the more anterior ones are shorter than 
those behind ; mesial septum slightly less than half the length of the entering valve. 
Usual length, 1 inch 4 lines; proportional width, -8°,; depth of receiving valve, 
35 ; length of entering valve, =85,; depth of entering valve, 52°. Surface punc- 
tations, about 18 or 19 in the space of one line. 
Every word of the above description will apply as well to the 
varieties of the living W. flavescens of Hobson’s Bay as to the 
fossil, except the punctation, which is, I think, conspicuously 
coarser in the fossil, being about 27 or 28 to the line in W. flaves- 
cens. ‘There is another Tertiary species very like this in our beds, 
but easily distinguished by the sharp angularity of the sides of the 
beak. I should have thought Mr. Davidson’s W. Garibaldiana 
identical with this species, but, as in a letter I have seen from him 
to the Rey. Mr. Tennison- Woods he thinks differently, I use for the 
present form my old name macropora, referring to the coarse 
punctation of the surface, which is conspicuously larger and with 
fewer openings in a given space than in the recent species. 
There are many varieties in the relation of length to width, 
gibbosity, and variations from pentagonal to ovate form in this 
species as in the recent W. flavescens. 
Very common in the Older Pliocene Tertiary strata of Flemington ; 
more rare in Oligocene beds between Mount Eliza and Mount 
Martha. 
EXPLANATION OF FIGURES. 
Plate XLIII.—Fig. 4, average size and shape of internal cast, receiving valve natural size. 
Fig. 4a, side view of same specimen. Fig. 46, front margin of same specimen (the upward 
angular sinus at the end of the two main ridges usually more strongly marked as compared with 
the others). Fig. 4c, view of same specimen, showing the entering valve with mesial septum 
(the three mesial ridges usually more distinctly separated from the lateral ones by a rather 
wider triangular space). Fig. 4d, half a line of surface magnified to show the size and number 
of the pores (compared with Fig. 5 showing a similar space similarly magnified of the recent 
W. flavescens). Fig. 6, smaller more ovate specimen, natural size, receiving valve. Fig. 6a, view 
of entering valve of same specimen. Fig. 66, front view of both valves. Fig. 6c, side view of 
both valves. 
Freprerick McCoy. 
fia 
