106 ON A NEW SPECIES OF TREE-FROO. [May 17, 



2. Description of a new Tree-Frog of the Genus Hjjla, from 

 British Guiana, carrying eggs on the back. By 

 G. A. BOULENGER, F.R.S., V.P.Z.S. 



[Received April 30, 1904.] 



(Plate V.) 



Hyla evansi. 



Tongue subcircular, slightly nicked behind, slightly free behind 

 and on the sides. Vomerine teeth in a strong transverse series, 

 narrowly interrupted in the middle, between the very large 

 ehoanae. Head as long as broad ; snout obtusely pointed, a little 

 longer than the diameter of the orbit ; canthus rostralis strong, 

 straight ; loreal region very oblique and concave ; nosti-il much 

 nearer the tip of the snout than the eye ; interorbital region 

 slightly concave, neaily as broad as the upper eyelid ; tympanum 

 very distinct, three-fifths the diameter of the eye. Fingers free ; 

 no distinct rudiment of pollex ; toes three-fourths webbed, the web 

 reaching the disks of the third and fifth, two last phalanges of 

 fourth free ; disks a little smaller than the tympanum ; no tarsal 

 fold. Skin finely granulate above, more coarsely on the belly and 

 under the thighs, smooth on the throat. Brown above, speckled 

 and spotted with darker, limbs with regular dark cross-bai's ; 

 white beneath, throat, breast, and limbs speckled with brown. 



From snout to vent 75 millim. 



The unique specimen, a female, cai-ries its eggs on the back, 

 fitting into shallow hexagonal impressions in the skin ; these eggs, 

 22 in number, measure 8 or 9 millim. in diameter, and contain 

 tailed larvae with rudimentary limbs and with allantois-like 

 membranous respiratory organs. In this it agrees with Hyla 

 goeldii Blgr.*, to which it is nearly related, and with Ceratohyla 

 huhcdus Esp.t 



This remarkable Frog was obtained at the end of November, 

 1902, at Groete Creek, Essequibo, by Dr. R. Evans, who has 

 kindly presented it to the British Museum,together with a sketch 

 made from the fresh specimen, and showing the embryos in 

 position ; these have unfortunately come off in transit. 



EXPLANATION OP PLATE V. 

 Syla evansi, sp. iiov. Natural size. 



* Cf. Boulenger, P. Z. S. 1805, p. 209, pi. x. figs. 1-3. 

 t Cf. Boulenger, P. Z. S. 1903, ii. p. 115, fig. 8. 



