SOLOMON ISLANDS. 61 



R. opisthodon Blgr., Boulenger (Trans. ZooL soc. London, 1888, 12, p. 51) quotes 

 the following from Guppy's field 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 contained a young frog, 

 about 4 lines 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 be branchiae. On my rupturing the ball or egg in which the 

 little animal was doubled up, the tiny frog took a marvellous leap into its exis- 

 tence, and disappeared before I could catch it." 



In addition to the above Boulenger observes : — 



"In illustration of this interesting observation, Mr. Guppy sent several 

 ova and recently hatched young, which are to be referred without the slightest 

 doubt to Rana opisthodon. The ovum, which measures from 6 to 10 millim. 

 in diameter, is a transparent spherical capsule in which the young frog is coiled 

 up in the same way as figured by Peters ^ in Hylodes tnartinicensis; but none of 

 the specimens, which are in an advanced stage of development, show anything 

 of a tail. There are no gills, but on the side of the abdomen are several regular 

 transverse folds (which in their arrangement remind of the gill-openings of 

 Plagiostomous Fishes), the function of which perhaps is that of breathing- 

 organs, like the tail of Hylodes. The tip of the snout is furnished with a small 

 conical protuberance, projecting slightly through the delicate envelope of the 

 egg, and evidently used to perforate that envelope, as is shown by one of the 

 specimens." 



The characteristic genus Cornufer is represented by four species, two of 

 which are autocthonous; and in one species of these, C. solomonis Blgr., the 

 describer indicates that a probable intra-oval metamorphosis also takes place, 

 owing to the condition of the ova in the ducts. It is of great importance to 

 emphasize the fact that here, as in New Ciuinea, we have so prominent this 

 adaptation to life in a region where standing water in the shape of ponds or 

 lakes is rare. From the steep configuration of the islands, it becomes e\'ident 

 that fresh-water must almost always occur in the form of swift-running streams. 

 It is well to recall again van Kampen's suggestion that the assumption of this 

 mode of reproduction has played a very important part in permitting amphi- 

 bians to extend here to the present frontier of their range. 



' Mon. Bcrl. acad., 1876, p. 714, fig. 2. 



