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Show 526 MR. G. A. BOULENGER O N N E W [June 6, I am glad to be able to supplement this description of the adult with an account of the very remarkable larval characters furnished by a specimen, undoubtedly of the same species, at the close of the larval period, obtained by Mr. Everett at Bongon, N. Borneo. The breast is covered with a large sucking-disk, free on its borders, truncate in front. The lips are much developed, not fringed, and armed with numerous series of horny teeth forming 3 uninterrupted and 8 paired rows on the upper lip, and 4 uninterrupted and 1 interrupted rows in the lower lip, disposed as shown in the figure. The horny beak is formed of an upper and a lower mandible, both of which are angular, smooth, and very finely denticulate at the edge. The larva is so far advanced that I am unable to say anything of the other larval characters. But in the important points of the structure of the mouth and ventral disk it shows the greatest resemblance to some hitherto undetermined larvae from Bantam, Java, which I described and figured in 1882 (Cat. Batr. Ecaud. p. 89). At that time the only Frog known to inhabit Java that possessed fully webbed toes dilated into large disks, as shown by one of the larvae, was Rhacophorus reinwardti; and I therefore referred them " provisionally, not without doubt," to that species. That this reserve was warranted, is shown by the discovery in Java soon after of a Frog, Rana masonii, Blgr. (=jerboa, Gthr.), agreeing in the above points with the larvae in question, which I have now no doubt belong to it. Numerous larvae of an allied species, R. whiteheads, Blgr., at all stages of development, hence easily determinable, were collected by Mr. Everett in mountain-streams flowing into the Sarawak and Baram Rivers and at Bongon. They differ, however, from the larva above described in having both upper and lower mandible formed of two pieces, separated in the middle line by a considerable interspace; these horny pieces differ besides in being ribbed and strongly toothed. Somewhat similar larvae, but with the lower mandible formed of a single piece, have been recently described and figured by Mocquard (Nouv. Arch, du Mus. 3, ii. 1890, p. 154, pi. xi. fig. 4) in his paper on the Reptiles and Batrachians of Kina Balu and referred by him, rightly I think, to his Ixalus nubilus ( = Rana natatrix, Gthr.). Another larva with ventral disk, and agreeing very closely in the buccal characters with that of R. jerboa and cavitympanum, was obtained by M . Fea in the Kakhien hills, Upper Burma, and referred by me to Rana latopalmata, Blgr. (afghana, Gthr.). I have since found three specimens of the latter larva, from Dar-jeeling, in the late Mr. Day's collection. W e are therefore now acquainted with five species with a ventral disk in the larval stage, and all five belong to species of the genus Rana in which the toes are fully webbed and the digits strongly dilated. They may be distinguished by means of the following synopsis :- |