﻿204 
  P. 
  A. 
  BUXTON. 
  

  

  3. 
  Cyprinodon 
  spp. 
  (family 
  Cyprinodontidae). 
  Eleven 
  specimens 
  of 
  

   C. 
  calaritanus, 
  Kishon 
  marshes, 
  July 
  ; 
  21 
  specimens 
  of 
  C. 
  sophiae, 
  Beisan, 
  March 
  

   and 
  June 
  ; 
  35 
  specimens 
  of 
  C. 
  fasciatus, 
  Beisan, 
  March 
  and 
  June. 
  As 
  the 
  feeding 
  

   habits 
  of 
  these 
  three 
  species 
  seem 
  to 
  be 
  very 
  similar 
  I 
  shall 
  deal 
  collectively 
  with 
  the 
  

   results 
  of 
  dissection 
  of 
  the 
  67 
  specimens. 
  I 
  found 
  filamentous 
  algae 
  in 
  42 
  individuals 
  ; 
  

   diatoms 
  in 
  35 
  ; 
  Cladocera, 
  Ostracoda 
  and 
  small 
  Nematocerous 
  larvae 
  in 
  25-30 
  ; 
  

   large 
  quantities 
  of 
  fine 
  grit 
  in 
  18 
  ; 
  Copepods 
  in 
  12 
  ; 
  small 
  Nematocerous 
  pupae 
  or 
  

   small 
  beetle 
  larvae 
  in 
  8 
  ; 
  insect 
  remains 
  in 
  7 
  ; 
  small 
  adult 
  Nematocera 
  in 
  6 
  ; 
  adult 
  

   Mymarids 
  in 
  5 
  ; 
  adult 
  thrips 
  in 
  3 
  ; 
  snails 
  or 
  small 
  adult 
  calyptrate 
  Diptera 
  in 
  2 
  ; 
  and 
  

   the 
  following 
  only 
  in 
  one 
  fish 
  each, 
  water-boatman, 
  Hydrachnid, 
  minute 
  dragonfly 
  

   larvae, 
  Difflugia 
  and 
  fish 
  eggs. 
  The 
  small 
  Nematocerous 
  larvae 
  have 
  been 
  identified 
  

   by 
  Mr. 
  F. 
  W. 
  Edwards 
  as 
  almost 
  certainly 
  those 
  of 
  a 
  species 
  of 
  Corynoneura 
  (Chirono- 
  

   minae), 
  or 
  possibly 
  Leptoconops. 
  The 
  small 
  pupae 
  are 
  probably 
  the 
  same, 
  as 
  larvae 
  

   and 
  pupae 
  were 
  often 
  found 
  in 
  the 
  same 
  fish. 
  It 
  is 
  remarkable 
  that 
  if 
  half 
  a 
  dozen 
  

   Cyprinodon 
  of 
  one 
  species 
  are 
  caught 
  at 
  the 
  same 
  time 
  and 
  place 
  and 
  examined, 
  one 
  

   will 
  be 
  found 
  crammed 
  with 
  Copepods, 
  another 
  with 
  Nematocerous 
  larvae, 
  another 
  

   with 
  filamentous 
  algae 
  and 
  diatoms 
  and 
  another 
  with 
  grit. 
  It 
  appears 
  that 
  individuals 
  

   prefer 
  to 
  make 
  a 
  meal 
  completely 
  from 
  one 
  type 
  of 
  food. 
  The 
  conclusion 
  I 
  draw 
  is 
  

   that 
  Cyprinodon 
  is 
  almost 
  omnivorous 
  and 
  will 
  eat 
  anything 
  which 
  is 
  in 
  season 
  ; 
  the 
  

   small 
  Crustacea 
  (Copepods, 
  Ostracods 
  and 
  Cladocera) 
  are 
  much 
  more 
  abundant 
  in 
  

   spring 
  than 
  in 
  summer, 
  and 
  accordingly 
  are 
  common 
  constituents 
  of 
  the 
  fish's 
  diet 
  

   only 
  in 
  spring. 
  On 
  the 
  other 
  hand, 
  winged 
  insects, 
  such 
  as 
  Mymarids, 
  water-boatmen, 
  

   adult 
  Diptera 
  and 
  thrips, 
  are 
  much 
  more 
  commonly 
  found 
  in 
  summer 
  than 
  winter. 
  

   Further 
  Cyprinodon 
  takes 
  its-food 
  at 
  all 
  levels 
  ; 
  the 
  Ostracods 
  and 
  Corynoneura 
  (?) 
  

   larvae 
  from 
  the 
  bottom 
  ; 
  the 
  Copepods 
  and 
  Cladocera 
  probably 
  from 
  midwater 
  ; 
  

   the 
  majority 
  of 
  the 
  winged 
  insects 
  either 
  floating 
  on 
  the 
  surface, 
  or 
  flying 
  above 
  it. 
  

   This 
  catholicity 
  of 
  taste 
  and 
  variety 
  in 
  methods 
  of 
  taking 
  food 
  are 
  points 
  in 
  favour 
  

   of 
  Cyprinodon, 
  because 
  they 
  must 
  enable 
  it 
  to 
  continue 
  to 
  exist 
  in 
  water 
  in 
  spite 
  of 
  

   changing 
  conditions. 
  It 
  appears 
  that 
  Cyprinodon 
  is 
  resistant 
  to 
  considerable 
  changes 
  

   in 
  the 
  salinity 
  of 
  the 
  water 
  in 
  which 
  it 
  is 
  living, 
  though 
  I 
  have 
  no 
  detailed 
  observations 
  

   on 
  this 
  point. 
  Certainly 
  it 
  thrives 
  all 
  through 
  the 
  summer 
  in 
  shallow 
  marshes 
  which 
  

   are 
  rapidly 
  diminishing 
  in 
  size, 
  and 
  it 
  is 
  known 
  that 
  some 
  of 
  the 
  species 
  live 
  in 
  hot 
  

   springs. 
  It 
  is 
  disappointing 
  that 
  we 
  have 
  obtained 
  no 
  definite 
  evidence 
  of 
  its 
  taking 
  

   mosquito 
  larvae. 
  

  

  It 
  appears 
  unlikely 
  that 
  we 
  shall 
  find 
  any 
  other 
  more 
  suitable 
  fish 
  among 
  our 
  

   native 
  species. 
  There 
  are 
  small 
  members 
  of 
  the 
  genera 
  Barbus, 
  Cobites 
  and 
  Blennius, 
  

   but 
  probably 
  they 
  are 
  bottom-feeders, 
  and 
  not 
  sufficiently 
  active 
  and 
  voracious 
  for 
  

   our 
  purpose. 
  

  

  So 
  much 
  for 
  the 
  result 
  of 
  dissection 
  : 
  we 
  have 
  failed 
  to 
  find 
  Culicid 
  larvae 
  in 
  any 
  

   of 
  the 
  fish 
  dissected. 
  The 
  results 
  of 
  field 
  observations 
  are 
  more 
  encouraging. 
  In 
  

   the 
  marshes 
  at 
  the 
  mouth 
  of 
  the 
  river 
  Kishon, 
  in 
  July 
  1921, 
  Ochlerotatus 
  caspius 
  

   was 
  breeding 
  in 
  the 
  greatest 
  profusion 
  in 
  isolated 
  cows' 
  footprints 
  among 
  the 
  Juncus 
  ; 
  

   wherever 
  the 
  footprint 
  was 
  connected 
  by 
  water 
  with 
  the 
  main 
  body 
  of 
  the 
  marsh 
  

   no 
  larvae 
  could 
  be 
  found 
  ; 
  they 
  were 
  also 
  absent 
  from 
  the 
  shallows 
  of 
  the 
  marsh 
  

   itself. 
  This 
  I 
  attributed 
  to 
  the 
  fact 
  that 
  Cyprinodon 
  calaritanus 
  and 
  young 
  Tilapia 
  

   zillii 
  swarmed 
  in 
  all 
  shallow 
  places. 
  At 
  the 
  same 
  time 
  larvae 
  of 
  Anopheles 
  were 
  

   quite 
  common 
  in 
  floating 
  vegetation 
  in 
  the 
  marsh. 
  At 
  Beisan, 
  in 
  June 
  1922, 
  the 
  

   larvae 
  of 
  Culex 
  perexiguus 
  and 
  0. 
  caspius 
  were 
  most 
  markedly 
  confined 
  to 
  footprints 
  

   and 
  other 
  small 
  collections 
  of 
  water 
  to 
  which 
  Cyprinodon 
  sophiae 
  and 
  C. 
  fasciatus 
  

   had 
  no 
  access. 
  In 
  the 
  larger 
  bodies 
  of 
  water 
  Culicine 
  larvae 
  could 
  never 
  be 
  found 
  

   at 
  all, 
  but 
  larvae 
  of 
  Anopheles 
  hyrcanus 
  (sinensis) 
  were 
  quite 
  numerous 
  in 
  patches 
  

   of 
  green 
  algae, 
  which 
  appeared 
  to 
  protect 
  them 
  from 
  the 
  Cyprinodon. 
  

  

  