72 THE NATURALIST IN AUSTRALIA. 
upon and kill other and larger lizards, such as Varani, refusing to come to close 
quarters with so formidable-looking an object as Chlamydosaurus, when it turns upon 
them with gaping mouth and suddenly erected frill. The erection of the feathers of 
an owl or the fur of a cat is correlated with a like “scaring” function, but the 
inflation of the hood of the Cobra, and in a less degree the neck-membranes of other 
snakes, furnishes, perhaps, a more appropriate analogy. In one other Australian 
species, Amphibolurus barbatus, commonly known as the Jew Lizard, which is also 
figured and described in this Chapter, the throat membrane is likewise inflated under 
the influence of irritation in such a manner as almost to constitute a frill, As 
hereafter recorded, in fact, this species, in districts south of the habitat of 
Chlamydosaurus, is commonly distinguished by the popular name of the Frilled 
Lizard. 
It is worthy of note with reference to the elevation and depression of the 
membranous frill of Chlamydosaurus that the species is not unfrequently delineated in 
natural history works with this structure more or less fully extended, but with the 
mouth completely closed. The author has also observed mounted specimens in 
museums displaying a corresponding relationship of the organ and structure indicated. 
As a matter of fact, the opening of the mouth and the erection of the frill are 
synchronous actions which cannot be exercised independently of one another. An 
explanation of this circumstance is afforded by the presence of slender processes of 
the hyoid bone which extend on either side through the walls of the membranous 
frill. The relative elevation of the frill is consequently in direct proportion with 
the depression of the mandible, and it is only under the condition of the mouth 
being opened to its widest extent that the frill is so conspicuously displayed as to 
stand out at a right angle from the animal’s neck, as indicated in several of the 
accompanying illustrations. 
Although presenting so weird and formidable an appearance, the Frilled 
Lizard possesses but feeble powers of aggression. Its teeth are small, the jaws 
comparatively weak, and it is but rarely that the animal attempts to bite, relying 
apparently on the discomfiture and retreat of its would-be assailants through the 
terror-striking appearance of its gaping jaws and erected frill. Individual specimens 
were, however, found by the author to differ materially in the exercise of their 
defensive or aggressive proclivities. With the majority of some half-a-dozen examples 
kept in confinement the non-aggressive form of defence was alone displayed. Two 
exceptional individuals, however, manifested an essentially hostile and pugnacious 
