214 G. A. BoOULENGER, 
far as my knowledge goes, is unique in the family Hylidae. It is 
mentioned in the generic definition of Ayla that the omosternum is 
cartilaginous, and so it is in H. caerulea. But the males of H. in- 
frafrenata are provided with a sharp pointed process in the middle 
of the breast, at the base of the vocal sac, and this process, which 
can easily be felt under the skin and shows very distinety in 
somewhat shrivelled up specimens, is formed by an ossification of the 
omosternum; this bone is slightly curved upwards in front, and its 
posterior part penetrates between the praecoracoids.. How far this 
remarkable structure is connected with the nuptial embrace can 
only be determined by and examination of specimens in copula. 
As regards the nuptial horny excrescences on the inner side of 
the first finger, which are similar in appearance to those of our 
common frog, Rana temporaria, it is desirable to state here that a 
difference on which the late Prof. BoETTGER partly based his var. 
tenuigranulata‘), from Halmaheira and Ternate, is not a constant one, 
since the two groups of rugosities may be perfectly separated from each 
other, narrowly connected, or fused together to form an uninterrupted 
patch. I may even note that in one specimen, from Bowen, the patches 
are distinct on the right side and continuous on the left. "T’he other 
characters on which the var. tenuigranulata are based, viz. the tuber- 
cular granulation of the upper parts and the relative size of the 
digital disks and the tympanum, I find to occur likewise in some 
specimens from other parts of the habitat, so that, in my opinion, it 
does not deserve to stand even as a geographical variety. I also 
regard H. aruensis, Horst?) from the Aru Islands and Misol, and 
H. sangwinolenta, van Kampen?), from New Guinea, as further 
synonyms of A. infrafrenata. 
The same is not the case with the tree-frog from the Bismarck 
Archipelago, for which WERNER has proposed the name H. dolichopsis, 
var. pollicaris*), in allusion to the presence of a projeceting rudiment 
of pollex, of which no trace is to be seen in the otherwise similar 
specimens from New Guinea and the Moluccas. The extremity of 
the metacarpal of the pollex is pointed and bent outwards at an 
oblique angle to the axis of the bone, and is indicated externally 
by a distinet knob on the inner side of the inner finger. This 
1) Zool. Anz., 18955 p- 136. 
2) Notes Leyd. Mus., Vol. 5, 1883, p. 342. 
3) Nova Guinea, Vol. 9, Zool., p. 33, pl. 11 fig. 3 (1909). 
4) Zool. Anz., 1898, p. 554. 
