﻿EGGS. 
  79 
  

  

  outer 
  surface 
  of 
  their 
  remains. 
  In 
  Bontbinator, 
  Hi/la, 
  

   and 
  Bana 
  the 
  embryo 
  develops 
  much 
  further 
  Tvithin 
  

   the 
  egg-, 
  and 
  becomes 
  Hberated 
  by 
  its 
  own 
  action. 
  

  

  In 
  Alytes, 
  which 
  is 
  exceptional 
  among 
  European 
  

   Batrachians 
  in 
  the 
  eggs 
  being 
  laid 
  on 
  land 
  in 
  strings, 
  

   taken 
  charge 
  of 
  by 
  the 
  male 
  parent, 
  who 
  carries 
  them 
  

   about 
  twisted 
  rouud 
  the 
  legs, 
  all 
  the 
  embryonic 
  stages 
  

   are 
  passed 
  through 
  within 
  the 
  egg, 
  and 
  the 
  young 
  is 
  

   born 
  as 
  a 
  true 
  tadpole. 
  Contrary 
  to 
  the 
  other 
  Batra- 
  

   chians, 
  the 
  food-yolk 
  of 
  which 
  is 
  in 
  insufficient 
  quantity 
  

   to 
  form 
  an 
  external 
  appendage 
  of 
  the 
  embryo, 
  we 
  find 
  

   here 
  a 
  large 
  yolk-sac. 
  These 
  eggs, 
  which 
  measure 
  

   three 
  and 
  a 
  half 
  or 
  four 
  millimetres 
  in 
  diameter, 
  are 
  

   of 
  a 
  uniform 
  yellow 
  colour, 
  and 
  are 
  protected 
  and 
  

   connected 
  in 
  rosary-like 
  fashion 
  by 
  a 
  comparativ^ely 
  

   tough 
  but 
  highly 
  elastic 
  transparent 
  investment, 
  

   which 
  represents 
  the 
  adhesive 
  envelop 
  of 
  the 
  typical 
  

   Batrachian 
  ovum, 
  and 
  contracts 
  thread- 
  or 
  hair-like 
  

   between 
  every 
  two 
  eggs. 
  

  

  The 
  following 
  synopsis 
  shows 
  the 
  principal 
  dif- 
  

   ferences 
  between 
  the 
  eggs 
  of 
  the 
  European 
  species, 
  

   and 
  will 
  serve 
  to 
  their 
  identification, 
  the 
  dimensions 
  

   given 
  being 
  those 
  of 
  recently 
  deposited 
  ones. 
  

  

  I. 
  With 
  large 
  unpigmented 
  vitelline 
  sphere, 
  3^ 
  — 
  4 
  

   millimetres 
  in 
  diameter, 
  laid 
  on 
  land 
  in 
  rosary- 
  

   like 
  strings, 
  carried 
  by 
  the 
  male 
  twisted 
  round 
  

   his 
  legs, 
  the 
  larva 
  leaving 
  the 
  envelops 
  in 
  an 
  

   advanced 
  condition 
  after 
  the 
  loss 
  of 
  the 
  ex- 
  

   ternal 
  gills 
  and 
  the 
  formation 
  of 
  the 
  spiraculum. 
  

  

  Alytes. 
  

  

  II. 
  With 
  small 
  vitelline 
  sphere 
  (1 
  — 
  3 
  millimetres 
  in 
  

  

  diameter), 
  entirely 
  or 
  partially 
  brown 
  or 
  black, 
  

  

  deposited 
  in 
  the 
  water, 
  the 
  embryo 
  leaving 
  the 
  

  

  envelops 
  with 
  external 
  gills 
  or 
  before 
  their 
  

  

  appearance. 
  

  

  A. 
  Deposited 
  singly 
  or 
  in 
  small 
  groups 
  of 
  two 
  to 
  

  

  twelve 
  ; 
  vitellus 
  brown 
  or 
  black 
  above, 
  white 
  

  

  or 
  yellowish 
  beneath, 
  the 
  embryo 
  leaving 
  the 
  

  

  