﻿10 
  FISHES 
  OF 
  THE 
  YELLOWSTONE 
  NATIONAL 
  PARK. 
  

  

  ARTIFICIAL 
  KEY 
  TO 
  THE 
  FISHES. 
  

  

  A. 
  Adipose 
  or 
  gristly 
  fin 
  on 
  back 
  situated 
  behind 
  a 
  soft, 
  jointed-rayed 
  dorsal 
  fin. 
  

  

  Salmonoid 
  fishes. 
  

  

  B. 
  Anterior 
  dorsal 
  fin 
  long 
  and 
  high, 
  with 
  19 
  or 
  20, 
  or 
  more, 
  fully 
  developed 
  rays. 
  

  

  Graylings 
  (Thymallidse). 
  

   a. 
  Coloration: 
  Back 
  bluish 
  gray 
  with 
  purplish 
  reflections; 
  sides 
  and 
  gill 
  covers 
  

   lighter, 
  with 
  purple 
  and 
  silvery 
  reflections, 
  beautifully 
  iridescent; 
  scales 
  with 
  

   pearly 
  luster; 
  belly 
  pure 
  white; 
  a 
  few 
  V-shaped 
  black 
  spots 
  between 
  head 
  

   and 
  middle 
  of 
  dorsal 
  fin 
  but 
  none 
  posteriorly; 
  two 
  oblong, 
  bluish 
  black 
  blotches 
  

   in 
  cleft 
  between 
  opercle 
  and 
  gill 
  membrane 
  rays 
  (branchiostegals), 
  more 
  pro- 
  

   nounced 
  in 
  the 
  male; 
  a 
  line 
  on 
  upper 
  border 
  of 
  belly 
  from 
  ventral 
  to 
  pectoral 
  

   fins, 
  dai-k 
  and 
  heavy 
  in 
  the 
  male, 
  very 
  faint 
  in 
  the 
  female. 
  Dorsal 
  fin 
  edged 
  

   with 
  a 
  red 
  or 
  rosy 
  border; 
  four 
  to 
  seven 
  rows 
  of 
  red 
  or 
  rosy 
  roundish 
  spots, 
  

   ocellated 
  with 
  white 
  between 
  the 
  dorsal 
  rays; 
  dark 
  blotches 
  forming 
  lines 
  be- 
  

   tween 
  the 
  rows 
  of 
  red 
  spots. 
  Ventral 
  fins 
  with 
  three 
  rose-colored, 
  branching 
  

   stripes 
  along 
  the 
  rays, 
  darker 
  between. 
  Pectoral 
  and 
  anal 
  fins 
  plain, 
  with 
  

  

  dark 
  border 
  Montana 
  grayling, 
  1. 
  

  

  BB. 
  Anterior 
  dorsal 
  fin 
  short 
  with 
  not 
  over 
  15 
  fully 
  developed 
  rays. 
  Salmon 
  family 
  

   (Salmonidae). 
  

   b. 
  Mouth 
  small, 
  teeth 
  sparse, 
  fine 
  bristle-like 
  or 
  none; 
  fewer 
  than 
  100 
  fully 
  de- 
  

   veloped 
  scales 
  in 
  a 
  lengthwise 
  series 
  from 
  the 
  upper 
  end 
  of 
  gill 
  opening 
  to 
  

   base 
  of 
  tail. 
  Whitefish 
  (Coregoninae). 
  

  

  c. 
  Scales 
  in 
  longitudinal 
  series 
  78 
  to 
  88; 
  coloration, 
  bluish 
  or 
  grayish 
  olivaceous 
  

  

  above, 
  silvery 
  on 
  sides, 
  whiter 
  below; 
  sometimes 
  with 
  dusky, 
  or 
  yellowish 
  

   or 
  brassy 
  tinge; 
  all 
  fins 
  usually 
  tipped 
  with 
  black; 
  tail 
  and 
  adipose 
  fins 
  

   bluish 
  or 
  olivaceous. 
  No 
  spots; 
  young 
  with 
  parr 
  marks. 
  

  

  Native 
  whitefish, 
  2. 
  

   bb. 
  Mouth 
  large, 
  teeth 
  strong 
  and 
  sharp; 
  scales 
  comparatively 
  small, 
  more 
  than 
  

   100 
  in 
  lengthwise 
  series. 
  Salmons, 
  trouts, 
  and 
  chars 
  (Salmoninae). 
  

  

  d. 
  Scales 
  in 
  lengthwise 
  series 
  fewer 
  than 
  200, 
  body 
  always 
  more 
  of 
  less 
  black 
  

  

  spotted. 
  (Salmo.) 
  

   e. 
  Scales 
  more 
  than 
  130 
  in 
  lengthwise 
  series; 
  body 
  profusely 
  black 
  spotted. 
  

   /. 
  Scales 
  in 
  lengthwise 
  series 
  about 
  160 
  to 
  170; 
  spots 
  rather 
  large, 
  pro- 
  

   fusely 
  scattered 
  and 
  irregular, 
  usually 
  none 
  on 
  the 
  belly; 
  red 
  

   blotches 
  on 
  the 
  lower 
  jaw 
  and 
  membrane 
  between 
  always 
  present. 
  

  

  Extremely 
  variable 
  in 
  coloration 
  and 
  form 
  Native 
  trout, 
  3. 
  

  

  ff. 
  Scales 
  in 
  lengthwise 
  series 
  about 
  135 
  to 
  145; 
  profusely 
  black 
  spotted 
  

   with 
  only 
  slight 
  if 
  any 
  appearance 
  of 
  red 
  on 
  and 
  between 
  lower 
  

   jaws. 
  Coloration 
  more 
  or 
  less 
  variable 
  but 
  usually 
  bluish 
  or 
  oli- 
  

   vaceous 
  above, 
  sides 
  silvery, 
  ever 
  j^ 
  where 
  profusely 
  spotted, 
  the 
  

   spots 
  extending 
  on 
  the 
  sides 
  of 
  the 
  belly 
  and 
  on 
  the 
  vertical 
  fins; 
  

   upper 
  ray 
  of 
  pectoral 
  spotted; 
  spots 
  on 
  tail 
  small, 
  belly 
  neai'ly 
  plain; 
  

   both 
  males 
  and 
  females 
  with 
  more 
  or 
  less 
  diffuse 
  red 
  or 
  rosy 
  lateral 
  

   band 
  and 
  blotches; 
  often 
  much 
  red 
  on 
  cheek 
  and 
  gill 
  cover. 
  

  

  Rainbow 
  trout, 
  4. 
  

   ee. 
  Scales 
  in 
  lengthwise 
  series 
  fewer 
  than 
  130. 
  Not 
  profusely 
  black 
  

   spotted; 
  no 
  rosy 
  wash, 
  band, 
  or 
  blotches 
  along 
  the 
  side. 
  

   g. 
  Body 
  comparatively 
  slender, 
  more 
  or 
  less 
  silvery, 
  with 
  no 
  ocel- 
  

   lated 
  red 
  spots; 
  black 
  spots 
  irregular 
  in 
  shape, 
  the 
  shape 
  deter- 
  

   mined 
  by 
  the 
  number 
  of 
  scales 
  occupied 
  ; 
  sometimes 
  cross, 
  double- 
  

   cross, 
  or 
  triple-cross 
  shape. 
  

   h. 
  Scales 
  in 
  lengthwise 
  series 
  118 
  to 
  130; 
  in 
  oblique 
  cross 
  series 
  from 
  

   lateral 
  line 
  to 
  upper 
  base 
  of 
  ventral 
  fin 
  26 
  to 
  30. 
  Upper 
  part 
  

  

  