﻿80 
  Prof. 
  M'lntosh's 
  Notes 
  from 
  the 
  

  

  occur 
  on 
  the 
  thorax 
  and 
  part 
  of 
  the 
  abdomen, 
  this 
  view 
  is 
  

   not 
  without 
  doubt. 
  

  

  So 
  far 
  as 
  can 
  be 
  observed 
  in 
  the 
  photographs 
  given 
  by 
  

   Sir 
  William 
  Turner*, 
  and 
  from 
  other 
  figures, 
  no 
  uniformity 
  

   exists 
  in 
  the 
  occurrence 
  of 
  the 
  fissures 
  in 
  the 
  ridges, 
  which 
  

   in 
  this 
  species 
  are 
  narrow 
  and 
  fine 
  in 
  front 
  in 
  comparison 
  

   with 
  those 
  in 
  the 
  common 
  rorqual, 
  and 
  still 
  more 
  in 
  contrast 
  

   with 
  the 
  massive 
  ridges 
  in 
  Megaptera. 
  Yet 
  in 
  the 
  common 
  

   rorqual 
  the 
  junction 
  of 
  two 
  ofthe 
  jugal 
  ridges 
  occurs 
  several 
  

   times 
  on 
  each 
  side, 
  and 
  in 
  their 
  course 
  backward 
  several 
  of 
  

   the 
  large 
  ridges 
  are 
  split 
  into 
  two. 
  

  

  2. 
  On 
  some 
  of 
  the 
  Species 
  q/ 
  Prionospio, 
  Malmgren. 
  

  

  A 
  Canadian 
  Frionospio, 
  dredged 
  by 
  Dr. 
  Whiteaves 
  in 
  the 
  

   Gulf 
  of 
  St. 
  Lawrence, 
  Canada, 
  presents 
  certain 
  differences 
  

   from 
  that 
  described 
  by 
  Malmgreu, 
  while 
  approaching 
  that 
  of 
  

   Sars. 
  No 
  complete 
  example 
  is 
  in 
  the 
  collection 
  and 
  no 
  

   satisfactory 
  fragment 
  of 
  the 
  posterior 
  end, 
  all 
  presenting 
  

   signs 
  of 
  mutilation 
  and 
  regeneration. 
  The 
  proboscis 
  was 
  

   extruded, 
  in 
  every 
  case, 
  so 
  that 
  the 
  snout 
  was 
  more 
  or 
  less 
  

   distorted, 
  the 
  protruded 
  organ 
  forming 
  a 
  button-like 
  process 
  

   on 
  the 
  end 
  of 
  a 
  short 
  cone. 
  The 
  snout 
  (PI. 
  VI. 
  fig. 
  1) 
  had 
  

   the 
  ordinary 
  truncate 
  anterior 
  border 
  without 
  a 
  trace 
  of 
  eyes, 
  

   but 
  on 
  the 
  dorsum 
  a 
  cephalic 
  ridge 
  extended 
  along 
  the 
  

   median 
  line 
  and 
  terminated 
  posteriorly 
  iu 
  a 
  pointed 
  process 
  

   like 
  an 
  adnate 
  tentacle 
  about 
  the 
  line 
  of 
  the 
  third 
  feet. 
  The 
  

   body 
  presented 
  the 
  normal 
  outline, 
  and 
  when 
  complete 
  

   probably 
  had 
  about 
  one 
  hundred 
  segments, 
  the 
  number 
  

   given 
  by 
  Malmgren 
  for 
  the 
  northern 
  species. 
  

  

  In 
  the 
  anterior 
  third 
  of 
  the 
  body 
  a 
  transverse 
  section 
  

   presents 
  well-developed 
  cuticle 
  and 
  hypoderm, 
  the 
  latter 
  

   especially 
  being 
  thick 
  in 
  the 
  lateral 
  processes 
  and 
  on 
  the 
  

   ventral 
  surface 
  external 
  to 
  and 
  at 
  the 
  sides 
  of 
  the 
  nerve- 
  

   cords. 
  The 
  dorsal 
  longitudinal 
  muscles 
  are 
  of 
  average 
  size, 
  

   and 
  the 
  inner 
  ends 
  are 
  slightly 
  tapered 
  as 
  they 
  approach 
  the 
  

   middle 
  line 
  above 
  the 
  dorsal 
  blood-vessel. 
  The 
  ventral 
  

   longitudinal 
  muscles, 
  which 
  occupy 
  a 
  Innited 
  elliptical 
  area, 
  

   are 
  also 
  of 
  average 
  bulk, 
  and 
  in 
  section 
  show 
  vertically 
  

   curved 
  fasciculi 
  externally 
  and 
  nearly 
  horizontal 
  fasciculi 
  

   internally. 
  In 
  this 
  region 
  a 
  powerful 
  series 
  of 
  fibres 
  passes 
  

   from 
  the 
  dorsum 
  about 
  the 
  middle 
  of 
  the 
  longitudinal 
  

   muscle, 
  which 
  is 
  pierced, 
  to 
  the 
  mid-ventral 
  surface, 
  probably 
  

  

  * 
  Op. 
  cif. 
  pp. 
  00 
  & 
  61. 
  

  

  