Upper Silurian.] PALZONTOLOGY OF VICTORIA. [Mollusea. 
In former works I have looked upon the Rhynchonella decempli- 
cata as a mere variety of R. diodonta and bidentata, which two latter 
(especially if their identity with R. borealis of Schlotheim, as 
suggested by Davidson, be established) may possibly be distin- 
guished with advantage, although I feel much inclined to hold to 
my old opinion. The &. decemplicata, however, as restricted, seems 
to be confined in England to that bed of sandstone at the base of 
the Wenlock series, forming the true base of the Upper Silurian 
system to which Professor Sedgwick and myself gave the name of 
May Hill sandstone after I had demonstrated its paleontological 
distinction from the Caradoc sandstone forming the top of the 
Lower Silurian or Cambrian series with which it had previously 
been confounded by Murchison and all other geologists. It is of 
great interest to find that precisely the same shell occurs in similar 
abundance in a precisely similar sandstone, marking the same 
geological horizon in Victoria. It was in fact one of the first fossils 
I identified on reaching Melbourne, proving that city to stand on 
the lower part of the Upper Silurian formations. 
Extremely abundant in the fine yellowish May Hill sandstone 
(B° 15) exposed in the road in section 44, parish of Wallan. Very 
common in the whitish May Hill sandstone (B” 17) near porphyry 
dyke, west of Mount Disappointment. 
EXPLANATION OF FIGURES. 
Plate XLVII.—Figs, 3, 4, 5, 6: several specimens of both valves, natural size. 
Pruate XLVII., Fias. 7, 8. 
NUCLEOSPIRA AUSTRALIS (McCoy). 
[Genus NUCLEOSPIRA (Hatt). (Sub-kingd. Mollusca. Class Palliobranchiata. Order 
Brachiopoda. Fam. Spiriferide.) 
Gen. Char.—Transversely oval, both valves convex with a narrow mesial sulcus in each ; 
hinge-line shorter than width of shell; beak of receiving valve sometimes perforated with a 
pit, forming a spoon-shaped chamber, with a strong cardinal tooth at base on each side ; a mesial 
septum from beak to front margin ; beak of entering valve with a large up-curved spatulate 
internal process grasped by the teeth of the opposite valve, into the cavity of the beak of which 
it extends; from the sides of this process extend the bases of the spiral apophyses resembling 
those of Spirifera ; a mesial septum from beak to front margin as in the receiving valve; surface 
smooth ; structure of shell fibro-punctate, extending into minute tubular spines on surface. ] 
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