58 



ANURA 



strongly dilated discs on the fingers and toes, e.g. Eana white- 

 headi, B. natatrix, and II. cavitymimnuin of Borneo, R. jcrhoa of 

 Java (this larva was originally described and figured as that of 

 Rhacophorus reimvarcUi), and B. afghana of the Himalayan system. 

 These tadpoles, at least those of R. Jerboa, are further remarkable 

 for having the " spiraeular " opening very far back on the left 

 side, nearer to the base of the tail than to the snout, so as to be 

 well out of the way when the creature has attached itself by the 

 adhesive disc. 



The mouth of the tadpoles of Anura is furnished with horny 

 armaments, substitutes for teeth. Their development and that 

 of the mouth in general has been well described by Gutzeit.^ In 

 the young larvae of Rana temporaria, one or two days after 

 hatching, a shallow groove appears above the conspicuous pair of 



adhesive organs. The groove 

 becomes rhombic in outline, 

 and when the mouth has 

 been formed in its centre, 

 the jaws appear in the 

 median corners of the 

 rhombus. The epidermis 

 then rises like a circular 

 wall around the jaws, and 

 ^''';nl!■~^^V^''°"V''''°^•*''^'"°•''^f ')'"'^^ divides into an upper and 



pole ot Raiui tejupomna, showing the trau.s- _ -i ^ 



verse rows of tmy horny teeth ; '2. three loWCr lip ; furroWS appear 



'^'^^^^^^^'^'''''y''^'^^^ them, and between 



these various papillae and 

 comb-like transverse plates of teeth. The papillae are pos- 

 sibly tactile organs, but although nerves enter them, nerve- 

 endings of a sensory nature have not yet been discovered. 

 On the fourth day the jaws become l^lack, by the tenth day 

 horny teeth have appeared upon all the plates of the mouth - 

 armature, and on the seventeenth day the mouth-apparatus lias 

 reached the configuration typical of the tadpole, which is now 

 about 14 mm. long. The number of liorny teeth in R. temporaria 

 amounts to about 640. These teeth are not cuticular products, 

 but cornified cells ; they are very small, and consist each of one 

 horny cell, which is shaped like a nightcap, the apex of which is 

 curved back and serrated. The little teeth are shed continu- 



Zcitscln 



iriss. Zool. xlix. 1889, p. 43. 



