On some tree-frogs allied to Hyla caerulea. 213 
they are not only larger than the tympanum, but nearly as large 
as the eye. Young specimens (No. 18 of table) have the diks consi- 
derably smaller than the tympanum, and this fact is specially worthy 
of note in view of the identification of H. infrafrenata with H. doli- 
chopsis. The subgular vocal sac of the male during the breeding 
season may be described as external. 
The green coloration (turning to blue or purple in spirit) is 
characteristic of this species, and seems far less subject to changes 
than in our European tree-frog. However, as I have mentioned before, 
white, dark-edged spots or streaks may be present or the sides of the 
body and limbs and on the upper lip; but there is not the least 
indication of the white or yellow border to the lower jaw which is 
constant in AH. infrafrenata. 
The second species, described almost simultaneously from a young 
specimen from Cape York, Queensland, as Ayla infrafrenata, and from 
adult from Amboina as Calamita dolichopsis, is easily distinguished 
by the longer hind limbs; when these are bent forwards against the 
body, the tibio-tarsal articulation reaches beyond the eye, often to 
the tip of snout or beyond (the temple or the eye in H. caerulea), 
and the crus or tibia is more than half the length of head and body 
(less than half in A. caerulea.. The snout is longer and the head 
is devoid of the dermal thickening, comparable to parotoids, on which 
the family Pelodryadidae was founded by GÜNTHER, and which give 
the common Australian species the peculiar appearance so well ren- 
dered in the Cambridge Natural History.) A white or yellow 
streak, edged with green, borders the lower lip; there is often a 
white or yellow, continuous or interrupted, sometimes wavy streak, 
along the inner edge of the tibia, this streak being well marked 
in the type of AH. infrafrenata, and I find it, interrupted, in a specimen 
from Amboina, the type locality for A. dolichopsis. How much the 
relative proportions of the tympanum and digital disks vary, the table 
of measurements here given sufficienty indicates. An osteological 
charakter, not previously pointed out, which distinguishes this species 
from H. caerulea resides in the nasal bones, which are mesially in 
contact or narrowly separated in the former, and very widely se- 
parated in the latter. 
Hyla infrafrenata is remarkable for a secondary sexual character 
which does not appear to have been noticed before and which, so 
1) H. Gapow, Amphibia and Reptiles, p. 199 (1901). 
