﻿On 
  new 
  Freshwater 
  Fishes 
  from 
  Portuguese 
  Guinea. 
  373 
  

  

  XLT. 
  — 
  Descriptions 
  of 
  new 
  Freshwater 
  Fishes 
  discovered 
  by 
  

   Dr. 
  W. 
  J. 
  Ansorge 
  in 
  Portuguese 
  Guinea. 
  By 
  G. 
  A. 
  

   BOULENGER, 
  F.R.S. 
  

  

  (Published 
  by 
  permission 
  of 
  tbe 
  Trustees 
  of 
  the 
  British 
  Museum.) 
  

  

  Representatives 
  of 
  the 
  following 
  six 
  new 
  species 
  form 
  

   part 
  of 
  a 
  large 
  collection 
  made 
  at 
  or 
  near 
  Batata 
  by 
  Dr. 
  

   Ansorge, 
  and 
  sent 
  by 
  him 
  to 
  the 
  British 
  Museum. 
  Some 
  

   specimens 
  are 
  from 
  the 
  Geba 
  River, 
  others 
  from 
  the 
  Culufi 
  

   River, 
  an 
  affluent 
  of 
  the 
  Geba. 
  

  

  Petersius 
  septentrionalis. 
  

  

  Depth 
  of 
  body 
  equal 
  to 
  length 
  of 
  head, 
  3^ 
  to 
  3| 
  times 
  in 
  

   total 
  length. 
  Head 
  twice 
  as 
  long 
  as 
  broad, 
  longer 
  than 
  deep 
  ; 
  

   lower 
  jaw 
  projecting 
  slightly 
  beyond 
  snout 
  ; 
  snout 
  shorter 
  

   than 
  eye, 
  which 
  is 
  2\ 
  times 
  in 
  length 
  of 
  head 
  and 
  exceeds 
  

   interorbital 
  width 
  ; 
  maxillary 
  extending 
  to 
  below 
  anterior 
  

   border 
  of 
  eye 
  ; 
  outer 
  prasmaxillary 
  teeth 
  4, 
  alternating 
  with 
  

   those 
  of 
  the 
  inner 
  row, 
  8 
  in 
  number; 
  8 
  teeth 
  in 
  lower 
  jaw. 
  

   Gill-rakers 
  moderately 
  long, 
  12 
  on 
  lower 
  part 
  of 
  anterior 
  

   arch. 
  Dorsal 
  II 
  7, 
  originating 
  above 
  ventral, 
  at 
  equal 
  

   distance 
  from 
  centre 
  of 
  eye 
  and 
  from 
  root 
  of 
  caudal. 
  Adipose 
  

   fin 
  very 
  small. 
  Anal 
  II[ 
  13-14. 
  Pectoral 
  nearly 
  as 
  long 
  as 
  

   head, 
  not 
  quite 
  reaching 
  ventral. 
  Caudal 
  deeply 
  forked. 
  

   Caudal 
  peduncle 
  a 
  little 
  longer 
  than 
  deep. 
  Scales 
  25-26 
  4 
  2 
  l, 
  1 
  

   or 
  1^ 
  between 
  lateral 
  line 
  and 
  ventral. 
  Silvery, 
  finely 
  

   speckled 
  with 
  brown 
  on 
  the 
  back 
  ; 
  a 
  blackish 
  lateral 
  band 
  ; 
  

   fins 
  white. 
  

  

  Total 
  length 
  45 
  mm. 
  

  

  Several 
  specimens 
  trom 
  the 
  Geba 
  and 
  Culufi 
  Rivers. 
  

  

  The 
  northernmost 
  species 
  of 
  the 
  genus. 
  Distinguished 
  

   from 
  all 
  the 
  species 
  with 
  alternating 
  prsemaxillary 
  teeth 
  and 
  

   a 
  complete 
  lateral 
  line 
  by 
  the 
  low 
  number 
  of 
  scales 
  in 
  the 
  

   lateral 
  line. 
  

  

  Distichodus 
  ansorgii. 
  

  

  Depth 
  of 
  body 
  3f 
  to 
  4^ 
  times 
  in 
  total 
  length, 
  length 
  of 
  

   head 
  4^- 
  to 
  5 
  times. 
  Iiead 
  longer 
  than 
  deep; 
  snout 
  rounded, 
  

   not 
  compressed, 
  projecting 
  very 
  slightly 
  beyond 
  mouth, 
  

   shorter 
  than 
  eye, 
  which 
  is 
  2\ 
  to 
  2| 
  times 
  in 
  length 
  of 
  head 
  

   and 
  equals 
  interorbital 
  width 
  ; 
  maxillary 
  extending 
  to 
  below 
  

   nostrils; 
  teeth 
  in 
  a 
  single 
  series, 
  20 
  or 
  22 
  in 
  each 
  jaw. 
  

  

  