﻿Arrangement 
  of 
  the 
  Family 
  Salmonidse. 
  

  

  407 
  

  

  sHglitly 
  notched 
  posteriorly, 
  and 
  correlated 
  with 
  this 
  the 
  

   n)ain 
  frontal 
  ridges 
  are 
  wide 
  apart 
  and 
  parallel, 
  whilst 
  the 
  

   supraorbital 
  flanges 
  are 
  narrow 
  and 
  taper 
  anteriorly. 
  In 
  the 
  

   Pacific 
  species 
  the 
  mesethmoid 
  is 
  much 
  smaller 
  and 
  is 
  forked 
  

   posteriorly, 
  the 
  frontal 
  ridges 
  converge 
  anteriorly 
  and 
  the 
  

   supraorbital 
  flanges 
  are 
  broad. 
  Thus 
  the 
  genus 
  Onco- 
  

   rhynchus, 
  Suckley, 
  can 
  be 
  no 
  longer 
  maintained, 
  unless 
  it 
  be 
  

   considered 
  that 
  the 
  cranial 
  characters 
  warrant 
  its 
  separation 
  

   from 
  Salmo 
  ; 
  in 
  that 
  case 
  Oncorhynchus 
  will 
  include 
  not 
  

   only 
  the 
  Pacific 
  Salmon, 
  but 
  the 
  Pacific 
  Trout 
  also. 
  Oiico- 
  

   rhynchus 
  is 
  said 
  to 
  have 
  a 
  longer 
  anal 
  fin 
  than 
  Salmo, 
  but 
  in 
  

  

  Fiff. 
  2. 
  

  

  Skulls 
  of 
  a. 
  Salmon 
  (Salmo 
  salar) 
  and 
  b. 
  Quinnat 
  {S. 
  quinnat). 
  As 
  in 
  

   fig. 
  1, 
  the 
  skulls 
  are 
  seen 
  fi'om 
  above 
  and 
  the 
  jawa, 
  facial 
  bones, 
  &c,, 
  

   have 
  been 
  removed. 
  The 
  skulls 
  are 
  those 
  of 
  adult 
  fish. 
  

  

  various 
  forms 
  of 
  S. 
  clarhii 
  I 
  count 
  8 
  to 
  11 
  branched 
  rays, 
  and 
  

   in 
  S. 
  {Oncorhynchus) 
  masou 
  10 
  to 
  12, 
  so 
  that 
  there 
  is 
  no 
  

   generic 
  distinction 
  between 
  these 
  species. 
  Nor 
  is 
  there 
  any 
  

   justification 
  for 
  Berg's 
  genus 
  Sahnothymus 
  (Ann. 
  Mus. 
  

   St. 
  Petersburg, 
  xii. 
  1907, 
  p. 
  502), 
  btised 
  on 
  Salmo 
  obtusi- 
  

   rostris, 
  Heck., 
  a 
  species 
  that 
  agrees 
  in 
  its 
  osteology 
  with 
  

   S. 
  trutta 
  and 
  S. 
  salar^ 
  and 
  may 
  be 
  regarded 
  as 
  the 
  repre- 
  

   sentative 
  of 
  the 
  latter 
  in 
  the 
  rivers 
  of 
  Dalmatia. 
  

  

  