﻿104 
  

  

  IJ^TRODTJCTION. 
  

  

  as 
  regards 
  their 
  degree 
  of 
  development 
  in 
  individuals 
  

   of 
  the 
  same 
  species, 
  and 
  their 
  arrangement 
  also 
  varies, 
  

   within 
  certain 
  limits, 
  irrespective 
  of 
  the 
  species. 
  I 
  

  

  Fig. 
  46. 
  

  

  Tadpoles 
  showing 
  sensory 
  canals. 
  . 
  A. 
  Rana 
  agilis. 
  b. 
  Pelodytes 
  

   pundatus. 
  c. 
  Alytes 
  obstetricans, 
  (From 
  ' 
  P. 
  Z. 
  S.,' 
  1891.) 
  

  

  have 
  found 
  them 
  usually 
  most 
  distinct 
  in 
  Pelodytes, 
  

   Pelohates 
  cultrijoes, 
  Rana 
  agilis, 
  R. 
  latastii, 
  and 
  Bom- 
  

   hinator 
  igneus 
  ; 
  least 
  in 
  Bufo. 
  I 
  append 
  figures 
  (Fig. 
  

   46) 
  of 
  tadpoles 
  of 
  Rana 
  agilis, 
  Pelodytes 
  punctatus, 
  

  

  