FASCICVLI MALATENSES 
141 
were haunted by a snake, Fropidonotus chrysargus^ two specimens of which 
were taken feeding on the spawn, despite the froth in which it was embedded. 
‘ The ova were quite devoid of colour, but the larvae soon assumed an almost 
uniform velvety black hue. The blue grey, so conspicuous on the belly of the 
adult, did not commence to make its appearance until the hind legs were fairly 
well developed, and was much less intense on the young frog than in the 
older specimens, being in very young individuals merely greyish-white. The 
dorsal surface of the adult so closely resembled the bark of the tree on which 
our specimens were taken, that I was unable to distinguish any of the individuals 
captured in the shadow of the buttresses, and only knew of their presence 
through their croaking or when they moved ; they were caught with a net in 
the water in the cavities, into which they dived when the trunk was tapped. 
^The resemblance, both above and below, between this species and 
Rhacophorus leprosus^ known from the mountains of Perak, is very close indeed, 
and is probably an instance of adaptive resemblance or ‘‘ convergence,” though 
the two frogs belong to closely allied genera, seeing that they both differ 
widely in appearance from the typical members of their respective genera. 
Their habits appear to be identical, ‘ and it is probable that a very close resem- 
blance also exists between their larvae, which live under very similar conditions, 
but it is not known whether the species are found together. It would almost 
seem as if there was some physiological connexion in these genera between a 
warty, bark-like dorsal surface, and a blue-grey belly, mottled with black, as 
it is most improbable, in consideration of the conditions under which these 
frogs live, with their bellies closely pressed against the bark of trees, that the 
conspicuous coloration of the ventral surface is an advertisement to enemiies. 
The coloration does not appear to be altogether parallel to that of Bomhinator^ 
as the species of the latter genus are said to display the brilliant orange or 
yellow of their bellies at the sides of the body, though the fable that they turn 
over on their backs to do so has been refuted.* It may be pointed out, how- 
ever, as Dr. Gadow himself confesses, that it is not always possible to induce 
tame individuals of this genus to adopt the ‘warning attitude,’ and that it is 
just possible that the attitude has primarily no connexion with the coloration of 
the ventral surface, as it is one paralleled by the common attitude of alarm of 
many animals which are soberly coloured below, even by certain Orthoptera 
and Crustaceans. In this case, boldly contrasting patterns on the belly of these 
four Batrachians may very well have a common origin in each instance, though 
we cannot at present state their object.’ 
1. Cf. L. Wray, Perak Museum Notes and Journ. Straits Branch Roy. Asiat. .Soc., 1890, p. 144. 
2. Gadow, Amphibia and Reptiles^ 156, 157. 
