508 Records of the Indian Museum. [Vot. XXIV, 



specimens is as a rule depressed in the form of a saucer. 

 Through the skin of this region are visible three large promi- 

 nences, which on dissection are found to be the extremeties of 

 two muscles ana a tendon. They represent (i) a strong tendon 

 (t) attached internally to the middle of the disc : it proceeds up- 

 wards for a short distance and then divides into two portions, 

 which are both attached to the vertebral column : and (ii) two 

 pairs of muscles composed of striated fibres which have similar 

 attachments at both ends but are quite distinct from the tendon. 

 By keeping the free border closely in touch with a fixed object 

 and then raising the central portion of the disc by contracting 

 the muscles, the animal can convert the whole structure into an 

 efficient organ of adhesion by creating a partial vacuum between 

 it and the fixed object, The function of the elastic tendon is to 

 counteract too strong contraction, which might tear the delicate 

 surrounding tissues. 



fig. I. — Disc and its musculature in Rana afghana. 



a. Slightly oblique lateral view of disc with its muscles and tendon. 



b. Anterior view of muscles and tendon after removal of disc. 



rf.=disc ; £.=tendon ; mas": i., and mus. 2.=muscles of disc, 

 (cf. Rec. Ind. Mus. XXIV, p. 47, fig. 9 b.) 



The structure of the disc is precisely similar in the tadpole 

 of Rana livida to that in R. afghana. 



The mechanism of the disc is the same as that already des- 

 cribed for the analogous structure in Garra 1 ; except that in the 

 fish the central portion of the disc is raised by the elevation of the 

 urohyal, without direct muscular action in the disc itself, which is 

 decidedly callous as a whole. 



The free borders are quite smooth in the tadpoles, but in 

 a section of the tissue under a high power (fig. 2) it is observed 

 that the outer cells are produced into minute processes which 

 are greatly flattened near the base and are somewhat pointed 

 towards the. end. These are covered by a chitinized cuticle. 

 Each of the spine-like outgrowths (s) is provided with a nucleus 

 at the base. The rest, of the epidermis (ep. d.) consists of a 

 large number of nuclei irregularly scattered in a homogenous 

 mass of cytoplasm. Below the epidermis is a loose connective 

 tissue in which nuclei are present at irregular intervals._ This 

 tissue (c. t.) is formed of a series of minute fibres, which in the 

 outer region run paralled to the epidermis, while internally they 



1 Hora, Rec. Ind. Mus. XXIV, p. 47 (1922.) 



