Upper Silurian.) PALMONTOLOGY OF VICTORIA. [Mollusea. 
very prominent scale-like lamine strongly curved over the ridges and showing a 
fine longitudinal striation under the lens. Width of very large specimen, 1 inch 9 
lines ; relPraore length of receiving valve, 6°, to 1%3;; length of entering valve, 
y53 depth of receiving valve, +3°,; of entering valve, ;°°,; three to four lamine 
in 1 line at 3 lines from beak ; ten longitudinal striz in 1 line. 
_, REFERENCE.—Delthyris sulcata, Hisinger, Lethea Suecica, t. 21, f. 6. 
wee. 
The much greater size of the Australian specimens than those 
commonly found in Europe is the only difference I can find between 
them, and this does not in the least disturb my opinion as to their 
identity, as I have been able to place in the National Museum for 
comparison a specimen from the Upper Silurian limestones of the 
typical Swedish locality, Klinteham, Gothland, 1 inch 4 lines wide. 
This specimen is of the receiving valve, has three ridges on each 
side, and in number of lamellz and longitudinal striz in a given 
space and all other characters it agrees with corresponding varieties 
from our Yarra beds, where all the European variations of relative 
length to width, acuteness or obtuseness of cardinal angles, con- 
vexity of valves, height of cardinal area, and number of lateral ribs 
are represented. I think it quite possible that the large Spirifera 
perlamellosa of the Lower Helderberg (= Wenlock) beds of New 
York may prove to be a local variety of this species, which is very 
characteristic of the Upper Silurian age. 
Common in the Wenlock shale of Yering, Upper Yarra. 
EXPLANATION OF FIGURES. 
Plate XLVI.—Fig. 9, front view of widest specimen, natural size. Fig. 9a, same specimen 
viewed from entering valve, showing cardinal area and acute lateral angle. Fig. 94, magnified 
portion of transverse scale-like lamelle (the longitudinal strie not represented). Fig. 10, view 
of receiving valve of specimen longer in proportion to the width, natural size. Fig. 10a, rostral 
view of same specimen, showing the cardinal area. 
Freprerick McCoy. 
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