HORN EXPEDITION—AMPHIBIA. 
161 
Our early specimens, secured during tlie dry season from water-lioles and 
burrows, were of a dirty yellow colour with indefinite darker splotclies upon the 
back, which was also marked with tubercles. 
In January and February, after rain had fallen, the change in colour was 
remarkable—so much so that at first I could hardly believe that the brightly- 
coloured and lively frog which was to be seen and heard in and about every water- 
hole was the same species as the lethargic, dull, and dirty form which we had but 
rarely seen before. 
I came across it first in a shallow clay-pan, to which I was attracted by a 
croak closely resembling that of the common (around Melbourne) Hyla aurea. At 
first no frogs could be I’ecognised, but whilst walking round the edge of the pool I 
saw bright emerald-green patches suddenly disappear beneath the surface. These 
were the heads of half-grown specimens of C. platycephahis. Their heads are 
coloured yellow with bright green markings, and so, as long as they remain still, 
they are not at first easy to detect in a pool of yellow^, muddy water dotted over 
with the bright, floating leaves of the nardoo plant {Marsika qtiadrifolia). 
Both the colour and the croak of these half-grown forms is not at all unlike 
that of a lightly-coloured Hyla mirea. As they grow older and larger they become 
somewhat duller, and the green patches more diffuse. The iris is golden with dark 
brown .specks, the tympanum a yellowish-brown and the sides of the body an 
orange-brown. The limbs are of the latter colour, though the hinder ones may be 
of a lighter tint, and the web is often distinctly pink. There is no difference in 
colour between males and females. 
Their colour on the banks of the water-pools, amongst sand and green herbage, 
is, at first sight, as deceptive as when they lie in the water. It is possible that 
this may serve, to a certain extent, to conceal them so long as they remain still, 
but it must also be noticed that when once he is accustomed to their appearance 
the human collector can easily distinguish them, even if they remain quiet, whilst 
when aware of your presence they at once move away, and are then, of course, 
easily seen. 
At all events they seem to pass through a seasonal change of colour, which 
accoixls, speaking generally, with that of their surroundings, becoming dull and 
dirty yellow as the vegetation withers and the water-holes dry up, and acquiring 
their brighter tints after rain, when everything is fre.sh and green. 
The Tadpole .—In one water-hole along the Opossum Creek, between 
Oodnadatta and Charlotte Waters, we found large tadpoles in May—that is, in 
