TADPOLES FROM SIAM. 39 



Dimensions. Total lengtii, 20 to 22 mm. Head and body, 7. 

 Depth of tail, 4. Expansion of lip, fully extended, 2x3. This struc- 

 ture may var}' in size in difForent broods. The drawing (A 2) is from 

 a large one and is by no means exaggerated, 



The tadpole spends most of its time, almost motionless, a short 

 distance below the surface of the water, rising at intervals to feed as 

 described. 



Microhijla achatina spawns throughout the rain}' season in 

 Bangkok. I have found the tadpoles in May, before the monsoon had 

 properly broken, and I have found them again in June and July, and 

 as late as October. The eggs are laid in masses and float on the 

 surface of the water. 



The young frog on leaving the water is of a light golden-brown 

 colour above, with a broad dark wav}"- vertebral band (A 3). ilany 

 specimens at this stage are practicallj' indistinguishable from the }'oung 

 of M. ornatii. After two or three weeks they begin to assume the reddish 

 tinge of adult life. 



Microhyla pulchra. 



Characters ; similar to M. ornata, but larger (vide, Flower, P.Z.S., 

 1899, p. 902). 



Colour, the same ; if anything, more transparent. As I have 



their colour, this cli.inge .iiiparently being dopeiuleiit upon their siirrounilinj:;^. 

 I coulil induce it invsclf by clianging tlie w.ifpi- in their tank. If it was nniddy, 

 tliey became olive, if clear, bhuk, and tlie change would be effected in a few 

 iiours time. 1 once found a conple of specimens that were dirty pink in 

 colour, so pale in fact that I tlionght I must iiave encountered some form of 

 albinism. 'J'hey were put aside l>y themselves, but on the following morning had 

 resumed their usual dark brown colouration. 



This jiower of clianging colour is not necessarily carried info later life. 

 The perfect form of CnUiilu jxihJira does not possess it, whilst exactly the con- 

 verse obtains with ItliKCujihontx leiicoiiij/st(i.r, tiie connnon Tree-Frog of Piang- 

 kok. The jierfect frog is probably as versatili! and rapid a cpiick change artist 

 as any frog known, and can vary from a pale yellow or almost pink to a dark 

 grey or brown in an exceedingly short space of time, yet its tadpole is unable 

 to vary in colour in the slightest degree. 



The size of tadpoles at tiie time of completing their nietamoi pilosis 

 may vary considurably, and depends chiefly u|)on their food supply. The 

 deserijitions here given are of well grown specimens, with tiie hind-limbs fully 

 developed, and before the protrusion of the fore-limbs. 



VOL. II, JUNE 191G. 



