260 ANURA CHAP. 



and possesses a pair of internal vocal sacs. Its specific name 

 refers to its predilection for forests of oak, among the dried leaves 

 of which it conceals itself so successfully that it is discovered with 

 difficulty. R.japonica of Eastern Asia is almost indistinguishable 

 from this American species and from the European R. acfilis. 



R. opisthodon of the Solomon Islands has the vomerine teeth 

 in two oblique series entirely behind the level of the choanae. 

 The general shape of this large frog is stout, the type specimen 

 of the male measuring 78, that of the female 125 mm. = 5 

 inches. The upper surface of the female is covered with small, 

 flat warts, that of the male is much smoother. The upper 

 parts are dark brown, while the under surface is brownish white. 

 The male has two internal vocal sacs. 



This species is interesting as affording another instance of 

 shortened development, the whole metamorphosis being gone 

 through within the egg. Mr. Guppy, its discoverer, has supplied 

 the following notes : " During a descent from one of the peaks of 

 Faro Island I stopped at a stream some 400 feet above the sea, 

 where my native boys collected from the moist crevices of the 

 rocks close to the water a number of transparent gelatinous 

 balls, rather smaller than a marble. Each of these balls con- 

 tained a young frog, about 4 inches in length, apparently fully 

 developed, with very long hind-legs and short fore-legs, no tail, 

 and bearing on the sides of the body small tufts of what seemed 

 to l)e branchiae. On my rupturing the ball or egg in which 

 the little animal was doubled up the tiny frog took a mar- 

 vellous leap into its existence, and disappeared before I could 

 catch it. On reaching the ship an hour after, I found that some 

 of the eggs which I had put in a tin had been ruptured on the 

 way by the jolting, and the liberated frogs were leaping about 

 with great activity. On placing some of them in an, open- 

 mouthed bottle, 8 inches long, I had to put the cover on, as they 

 kept leaping out." 



Boulenger * has figured and further described the eggs and 

 young. The egg measures 6-10 mm. in diameter, and is a trans- 

 parent capsule in which the young frog is coiled up in the same way 

 as figured by Peters in Hylodes martinicensis ; but none of the 

 specimens, which are in an advanced stage of development, 

 show anything of a tail. There are no gills, but on each side 



1 Trans. Zool. Soc. xii. 1884, p. 51. 



