6 ANNALS OF THE QUEENSLAND MUSEUM. 
v enture to assume that the average of the proportion of skull to 
carapace in Chelonians may be found in recent turtles — for example, 
in Chelone virgata. In these I find them to be 1 : 47. Since the 
length of the NotocJielone skull is at least 195 mm , it is thus 
proportionate to a carapace about 916 mm. long. Either then 
JVotochelone had an enormously disproportionate head, or the type 
was not much more than half grown. For myself, I should prefer 
the latter alternative. It seems not improbable that the carapace 
and the younger of the skulls were of about the same age. 
We have to thank an accident, resulting from superincumbent 
pressure, for an assurance of the existence of one important piece 
of internal structure, the fact of whose presence would have 
remained merely inferential. Resting on its mandible and, judging 
from the unequal level of that bone, with an inclination to the left 
side, the skull has yielded to the force applied to it from above. 
Anteriorly, as far back as the posterior limit of the frontal, it has 
been crushed down considerably below the level of the parietal s. 
The parietals themselves, that of the left side especially, have within 
a short distance from the sagittal suture been split longitudinally, 
and bent downwards, but have escaped depression along a narrow 
space on each side of the mid line. This space was evidently upheld 
by the vertical walls formed by parieto-pterygoid plates. The lateral 
extent of the premaxillaries cannot, in the absence of sutures, be 
defined and, to my regret, their palatal relations have not been laid 
open. The rostrum is prolonged to a distance of 35 mm. from the 
anterior nares, and its terminal margin is but slightly, if at all, 
unciform. The edge of the maxillary is uniformly simple without a 
trace of processes dentiform or other in the part uncovered, though 
in uncovering it the greatest care was taken to avoid obliterating 
them had they been present. It would seem that we have here a 
case analogous to those noticed by Mr. Boulenger when wisely 
suggesting that the loss of the sharp-edged mandibles present 
in certain Chelonians when young, and their substitution by molari- 
form alveoli in the adults may be accounted for by supposing it to be 
the result of a change from a carnivorous to a conchivorous diet. 
In the present case I am induced to submit that, if the absence of 
dentiform processes in the adult should be confirmed by subsequent 
acquaintance with NotocJielone, it resulted, not from a change of diet 
but from an increase in muscular power. Objects of prey so elusive 
