SILYBURA. 259 



body 30 to 35 times in total 

 length ; eye more than one 



third length of ocular S. nitida, p. 263. 



y' . 144-172 ventrals ; diameter of 

 body 25 to 32 times in total 



length S. ellioti, p. 265. 



/3. Rostral compressed, keeled above, 



at least two fifths length of 



shielded part of head ; snout 



acutely pointed. 



a. 150-168 ventrals ; diameter of 



body 26 to 32 times in total 



length ; caudal disk quite flat. "S". dindigalensis, p. 264. 

 /3'. 213 ventrals ; diameter of body 

 38 times in total length ; ros- 

 tral half length of shielded 



part of head <S'. macvorhynchus, p. 264. 



y . 180-188 ventrals ; diameter of 

 Dody 33 to 40 times in total 



length S. beddomii, p, 265. 



b' . Eye half length of ocular, or more ; 

 snout obtuse. 

 a" . Portion of rostral seen from above 

 longer than its distance from 

 frontal. 

 a. 144-157 ventrals ; diameter of 

 body 28 to 38 times in total 

 length ; rostral one third 

 length of shielded part of head. S. phipsonii, p. 266. 

 /3. 130-153 ventrals ; diameter of 

 body 25 to 32 times in total 

 length ; rostral not quite one 

 third length of shielded part 



of head S. myhendrce, p. 267. 



b". Portion of rostral visible from above 



as long as its distance from 



frontal. 



a. 142-150 ventrals ; diameter of 



body 30 to 32 times in total 



length S. 7nadurensis, p. 267. 



/3. 1 27-133 ventrals ; diameter of 

 body 25 to 33 times in total 



length S. rubromaculatct, p. 268. 



c". Portion of rostral visible from above 



shorter than its distance from 



frontal. 



a. 128-130 ventrals ; diameter of 



body 26 or 27 times in total 



length ; eye half length of 



ocular *S'. arcticeps, p. 268. 



^. 122-146 ventrals ; diameter of 

 body 21 to 29 times in total 

 length ; eye rather more than 



half length of ocular S. brevts, p. 268, 



C. 15 scales round the middle of the body ; 

 128-140 ventrals; diameter of body 24 to 



29 times in total length *S'. macrolepis, p. 269. 



S2 



