224 DR. MALCOLM SMITH ON 



larger than the eye. Fingers moderate, the tips swollen into very- 

 small discs, first as long as second, third as long as the snout ; subar- 

 ticular tubercles moderate. Hind limb moderate, the tibio-tarsal 

 articulation reaching to between the eye and the tip of the snout ; 

 heels slightly overlapping when the limbs are folded at right angles 

 to the body. Toes moderate, the tips dilated into small but very 

 distinct discs, nearly fully webbed, two phalanges of the fourth toe 

 free. A well marked tarsal fold; inner metatarsal tubercle moderate, 

 half the length of the fifth toe; no outer tubercle. 



Skin of the upper parts with rounded glandules or short 

 folds ; a strongs curved fold from the eye to the shoulder. 



Nasal bones in contact. 



Olive brown above, with lighter and darker markings ; a pale 

 bar between the eyes ; lips and limbs with dark bars. Below yellow- 

 ish white. 



Female, similar to the male, but without any enlargement of 

 the head or tooth-like projections to the lower jaw. 



Males with internal vocal sacs. 



Variation. Forty examples from the t}^pe locality shew but 

 little variation from each other. The first finger may be a little 

 longer than the second ; the hind limb in some males reaches only to 

 the eye, while in other (younger) specimens it reaches as far as the 

 nostril. 



Two examples have a broad yellow vertebral stripe. 



This frog is the smallest of the group. From. R. dorice it 

 differs in the enlargement of the head and tooth -like projections in 

 the lower jaw. From R. macrognathus and R.^ileata in the absence 

 of any postorbital prominence. 



Distribution. Besides on Koh Chang this frog has been found 

 on the neighbouring islands of Kut and Mehsi, and on the adjacent 

 mainland at Ok Yam. 



Its presence on the mainland, in view of the closely related 

 forms of this group, is of particular interest, for R. pileata, with its 

 very distinct occipital flap is found on the same coast only 125 km. 

 distant. 



JOURN. NAT. HIST. SOC. SIAM. 



