﻿MANUAL 
  OF 
  FISH-CULTURE. 
  

  

  255 
  

  

  lost. 
  As 
  the 
  gills 
  are 
  replaced 
  by 
  lungs 
  during 
  this 
  perioa, 
  it 
  is 
  essen- 
  

   tial 
  that 
  the 
  tadpoles 
  have 
  access 
  to 
  land 
  or 
  resting-places, 
  and 
  it 
  is 
  a 
  

   time 
  of 
  peculiar 
  difficulty 
  in 
  the 
  creature's 
  existence. 
  When 
  the 
  tail 
  

   is 
  almost 
  fully 
  resorbed, 
  the 
  purely 
  aquatic 
  life 
  is 
  forsaken 
  for 
  the 
  

   amphibious 
  and 
  the 
  food 
  is 
  changed 
  from 
  dead 
  to 
  living 
  matter, 
  which 
  

   must 
  demonstrate 
  its 
  living 
  condition 
  by 
  motion. 
  The 
  peculiarly 
  formed 
  

   tongue 
  — 
  loose 
  behind, 
  so 
  that 
  it 
  maybe 
  thrown 
  out 
  to 
  quite 
  a 
  distance 
  — 
  

   is 
  covered 
  with 
  a 
  viscid 
  secretion 
  so 
  that 
  the 
  frog 
  readily 
  captures 
  

   any 
  insects 
  or 
  small 
  animals 
  that 
  approach 
  it 
  closely. 
  Tadpoles 
  are 
  

   commonly 
  satisfied 
  to 
  wait 
  patiently 
  for 
  their 
  food, 
  and 
  even 
  the 
  adults 
  

   do 
  not 
  often 
  search 
  actively 
  for 
  food. 
  Sexual 
  maturity 
  is 
  reached 
  in 
  

   about 
  three 
  or 
  four 
  years, 
  being 
  latest 
  for 
  those 
  varieties 
  that 
  pass 
  the 
  

   first 
  winter 
  in 
  the 
  tadpole 
  stage. 
  It 
  is 
  generally 
  believed 
  that 
  frogs 
  

   live 
  for 
  12, 
  15, 
  or 
  even 
  20 
  years. 
  

  

  During 
  the 
  tadpole 
  stage 
  they 
  furnish 
  tempting 
  morsels 
  for 
  fish, 
  rep- 
  

   tiles, 
  some 
  mammals, 
  and 
  other 
  frogs, 
  and 
  esjiecially 
  for 
  wading 
  birds, 
  

   like 
  herons 
  and 
  cranes. 
  Their 
  defenseless 
  condition 
  and 
  the 
  shallow- 
  

   ness 
  of 
  their 
  natural 
  habitats 
  at 
  this 
  period 
  make 
  them 
  ready 
  prey, 
  

  

  Spring 
  Frog 
  or 
  Leopard 
  Frog 
  {Itana 
  riresceiis). 
  

  

  and 
  it 
  is 
  in 
  the 
  prevention 
  of 
  this 
  wholesale 
  destruction 
  that 
  man 
  may 
  

   profitably 
  intervene. 
  In 
  the 
  adult 
  frog 
  stage 
  the 
  relentless 
  pursuit 
  by 
  

   birds 
  and 
  reptiles 
  is 
  continued 
  until 
  of 
  the 
  hundreds 
  of 
  eggs 
  deposited 
  

   few 
  become 
  reproducing 
  individuals. 
  Only 
  sliglit 
  revenge 
  for 
  all 
  this 
  

   slaughter 
  can 
  be 
  taken. 
  They 
  may 
  occasionally 
  capture 
  disabled 
  fish 
  

   or 
  small 
  fish 
  of 
  sluggish 
  habits 
  found 
  in 
  the 
  mud 
  or 
  on 
  the 
  bottom, 
  and 
  

   instances 
  are 
  recorded 
  of 
  their 
  eating 
  snakes, 
  toads, 
  and 
  young 
  birds, 
  

   but 
  insects 
  and 
  lower 
  forms 
  are 
  their 
  staple 
  diet. 
  

  

  DESCRIPTIONS 
  OF 
  MARKETABLE 
  FROGS 
  OF 
  THE 
  UNITED 
  STATES. 
  

  

  The 
  species 
  of 
  frogs 
  commonly 
  eaten 
  are 
  the 
  bullfrog 
  {Rana 
  cates- 
  

   hiana), 
  the 
  green 
  frog 
  {Rana 
  clamata), 
  the 
  spring 
  frog 
  {Rana 
  virescens), 
  

   and 
  the 
  western 
  bullfrogs 
  {Rana 
  preiiosa 
  and 
  Rana 
  aurora). 
  

  

  The 
  following 
  references 
  to 
  their 
  geographical 
  distribution 
  and 
  brief 
  

   descriptions 
  of 
  their 
  color 
  and 
  form 
  have 
  mainly 
  been 
  extracted 
  from 
  

   Professor 
  Cope's 
  work 
  on 
  The 
  Batrachia 
  of 
  North 
  America 
  (Bulletin 
  

   No. 
  34, 
  U. 
  S. 
  National 
  Museum, 
  1889). 
  

  

  