Tertiary. | PALZONTOLOGY OF VICTORIA. (Mammalia. 
As in the Cachalot, the osteodentine of the pulp-cavity blends im- 
perceptibly with the dentine. The radiated bone corpuscles of the 
cement agree almost completely with those of the living Physeter 
and fossil Balenodon ; and there is, as in the latter, a clear colorless 
basis of the cement forming a conspicuous narrow band, where it 
fills the undulations formed by transverse sections of the longitudi- 
nal flutings of the dentine. The Balenodon, from beds of the same 
geological age as those affording our fossils (Older Pliocene), 
differs entirely in the greater proportion of the diameter occupied 
by the dentine. 
The magnificent specimen represented by our Figure 1 was dis- 
covered by Mr. J. F. Bailey, of Melbourne, in one of his many 
successful explorations of the strata at Mordialloc, and was by 
him presented to the National Museum, where it now bears his 
name as a well-merited compliment to his intelligent zeal and 
liberality. 
Rare in the ferruginous layers of the older Pliocene Tertiary 
strata of Mordialloc. 
EXPLANATION OF FIGURES. 
Plate LV.—Fig. 1, view of tooth, imperfect at upper end, natural size, showing the external 
surface, and base, and the small conical pulp-cayity. Fig. 1a, longitudinal and transverse sections 
of other side of same specimen, showing the spheroidal nodular structure of the osteodentine 
towards the middle below, the more solid dentine, with lines marking the form of the apex of 
the crown, and the coarse radiating fibrous external layer of cement. Fig. 14, surface ridging, 
magnified. Fig. 1c, cement tubes, magnified. Fig. 2, longitudinal section of another specimen, 
polished in one part and roughly fractured in the others, natural size. 
Pirate LY., Fia. 3. 
SQUALODON WILKINSONI (McCoy). 
Description.—(For hind, lobed teeth see Decade II., plate xi.) Anterior teeth 
with a long single cylindrical fang, and a short, conical, arched, moderately com- 
pressed crown having an oval section. Surface of crown highly polished, and 
marked with narrow, irregular, prominent, simple or branching, angular rugged 
longitudinal ridges, more numerous towards the base. Length of crown and root, 
about 1 inch 10 lines; length of crown, about 9 lines; longer diameter at base of 
crown, 5 lines; shorter or transverse diameter, 44 lines. 
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