SIR R. OWEN ON FOSSIL REMAINS OF MEGALANIA PRISOA. 
329 
The subject of figs. 10, 11, 12, Plate 15, is a metapodial with the family characters of 
that of figs. 5-8, Plate 14. It is from the same locality, shows the same colours and 
mineralized condition, and a similar, though inferior, proximal expansion ; but with 
extensions of the flattened articular surface on both right and left sides of the proximal 
end of the shaft, showing it to have been situated somewhere between the innermost 
and the outermost of the metapodial series. The length of this bone is 2 inches, 10 
lines=73 millims. ; its antero-posterior breadth at the proximal end is 28 millims. ; 
the same distal breadth is 20 millims. ; the tran verse proximal breadth is 20 millims., 
the same distal breadth is 28 millims. The distal articulation, c, is a hemispheroid 
condyle, with a prominence on each side of the base, for ligamentous attachment. 
The subject of figs. 13, 14, is also a metapodial, with an antero-posterior expanse 
of the proximal half of the shaft greater in degree than in the foregoing specimen, but 
less, in comparison with the length of the bone, than is the expanse shown in figs. 5 
and 7, Plate 14. The proximal articular surfaces, a , b, meet at an acute angle defining 
that end of the bone by a curved edge. The broader articular surface, fig. 13, a, is flat, 
the narrower one, fig. 14, b, is slightly convex. The expanse of the bone is from before 
backwards. The distal half of the shaft, above the condyle, is triedral. On the 
expanded part of the shaft is the oblong, smooth, seemingly articular surface, figs. 13, 
14, d, which bends round an angle of the beginning of the contracted part of the shaft. 
Another oblong, smooth prominence, fig. 13, e, is defined upon the opposite side. Two 
facets of the contracted part of the shaft meet at an obtuse ridge which terminates in 
an oblong smooth protuberance, fig. 13 ,f. On the opposite side of the distal end is a 
well defined oval tract, fig. 14, g. 
Of the phalanges I select a proximal, figs. 16, 17, and a distal or ungual, figs. 18, 19, 
specimen, figures of which, with those of the metapodial bones, may serve as guides in 
the recognition of similar evidences of the megalanian genus, and add to the know¬ 
ledge of the geographical distribution in Australia of this remarkable reptilian form. 
The proximal phalanx, figs. 16, 17, continues the character of unusual breadth of the 
upper end ; it gives transversely 35 millims., the antero-posterior diameter of the middle 
of the shaft being 12 millims. The proximal articular surface, fig. 17, «, is moderately 
concave, bounded on each side by a stout tuberosity. The distal trochlea, 20 millims. 
transversely by 10 millims., c, fig. 16, is feebly convex antero-posteriorly, more feebly 
concave transversely. It seems to have been a phalanx of a first or a fifth toe. 
Ungual phalanges of the intervening toes have a deeper trochlear proximal joint, 
fig. 18, a ; beyond this surface the bone is perforated by a transverse canal, b, the 
lower wall of which forms a cross bar, c, affording an insertional leverage to the flexor 
tendon. From each outlet of the canal a groove extends forward, subsiding at the 
roughened core of the claw. The metapodials of the chameleon approach in some pro¬ 
portions, though remotely, the megalanian peculiarities of the foot-bones, but a more 
close examination and extensive comparison of these parts of the reptilian skeleton are 
needed. 
2 u 
MDCCCLXXXVI. 
