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Show 1899.] BATRACHIANS O F T H E M A L A Y PENINSULA A N D SIAM. 903 lower crest deeper than the upper. The mouth has neither hard beak, labial teeth, or papillae, but consists of a simple upper lip and a contractile lower one. Colour. In life these tadpoles are transparent and almost colourless. The eyes and viscera are therefore very noticeable. But there are a number of minute yellowish-brown spots, particularly on the back, where they form a somewhat diamond-shaped figure, and on the muscular portion of the tail. Size. Length of body 7 mm.; width of body 4 mm.; length of tail 13 mm.; depth of tail 3 m m. The recently transformed young measure about 7*5 m m . from snout to vent. A remarkable feature of these tadpoles is that the hind feet are for a time completely webbed, the web is very fine and colourless; when the young frogs leave the water this web disappears. N.B.-At various times I have found in Penang some very remarkable tadpoles (Plate L X . figs. 2, 2a-2c), the affinities of which could not be conjectured, till, having made out the tadpole of Microhyla ornata, there seems no doubt they belong to some Engystomatoid Batrachian. Although the species they develop into is still unknown, I think it desirable to describe the tadpole in this paper. The first tadpoles with the spiraculum thus placed, and with this simple mouth, that I came across, I caught in Singapore early in 1896. At the time I imagined them to belong to Callula pulchra (and still do so), but was unable to prove it; on later occasions I have found these " transparent tadpoles" in Bangkok (where I was able to observe them grow into M. ornata), in the Dong Phya Fai, in Kedah, and on Penang Hill, all of which I have no doubt are of the genus Microhyla. These " transparent tadpoles " (of which I have observed four or five different species), besides differing in structure, differ entirely in habits from the tadpoles of the Ranidae and Bufonidae. Instead of passing a great deal of their time on the bottom, they are usually just under the surface of the water, continually opening and shutting their mouths; they are very delicate, and difficult to transport alive in a bottle even for a few miles. Description of " Transparent Tadpoles," Penang (Nov. and Dec. 1896). Form. The length of the body is about lj its width ; the length of the tail is from If- to If the length of the body. Nostrils. Distance of nostrils apart 1*4 mm.; distance from nostril to end of snout 2*5 mm.; distance from nostril to eye 4 mm. The nostrils are placed close together on the upper surface of the head, and are nearer the end of the snout than the eye. The distance to the eye is from 1^ to 1| the distance to the end of the snout. The distance between the nostrils is about £ the distance between the eyes. |
