﻿432 
  Prof. 
  M'Intosh 
  on 
  the 
  

  

  and 
  is 
  wholly 
  ventral, 
  though 
  with 
  the 
  same 
  immediate 
  

   relations, 
  viz., 
  the 
  external 
  (now 
  ventral) 
  chitinous 
  layer, 
  

   nnd 
  internally 
  the 
  fibres 
  of 
  the 
  oblique 
  muscle. 
  In 
  the 
  

   fresh 
  specimen 
  the 
  rapid 
  diminution 
  and 
  increase 
  of 
  each 
  

   muscle 
  and 
  the 
  perfect 
  continuity 
  of 
  the 
  fibres 
  are 
  well 
  

   shown. 
  Thereafter 
  it 
  rapidly 
  enlarges 
  and 
  approaches 
  the 
  

   middle 
  line, 
  assuming 
  an 
  ovoid 
  form 
  in 
  transverse 
  section 
  — 
  

   the 
  deepest 
  fasciculi 
  being 
  in 
  the 
  middle. 
  On 
  attaining 
  full 
  

   development 
  in 
  the 
  posterior 
  region, 
  the 
  size 
  exceeds 
  that 
  of 
  

   the 
  dorsal, 
  the 
  fasciculi 
  slanting 
  from 
  the 
  summit 
  of 
  the 
  

   nerve 
  near 
  the 
  median 
  line 
  outward 
  to 
  the 
  attachment 
  of 
  the 
  

   external 
  vertical 
  muscle. 
  The 
  outline 
  in 
  the 
  preparations 
  

   (transverse 
  sections) 
  is 
  convex 
  inferiorly 
  — 
  an 
  approach 
  to 
  

   the 
  condition 
  observed 
  at 
  the 
  commencement 
  of 
  the 
  anterior 
  

   region 
  of 
  the 
  body. 
  It 
  still 
  has 
  a 
  very 
  thin 
  chitinous 
  in- 
  

   vestment 
  externally, 
  and 
  the 
  oblique 
  muscle 
  bounds 
  it 
  

   internally, 
  except 
  the 
  ova 
  distend 
  the 
  body-wall 
  and 
  separate 
  

   them. 
  Toward 
  the 
  tip 
  of 
  the 
  tail 
  a 
  considerable 
  diminution 
  

   takes 
  place 
  before 
  its 
  termination. 
  

  

  In 
  the 
  ordinary 
  condition 
  of 
  the 
  snout, 
  as 
  well 
  as 
  during 
  

   the 
  development 
  of 
  the 
  peculiar 
  organs 
  on 
  the 
  sides 
  of 
  the 
  

   body, 
  a 
  granular 
  fluid 
  is 
  observed 
  oscillating 
  (under 
  com- 
  

   pression) 
  in 
  the 
  interior 
  of 
  both 
  cephalic 
  muscles 
  (median 
  

   and 
  lateral). 
  The 
  detached 
  globules 
  (which 
  roll 
  about) 
  

   seem 
  to 
  be 
  associated 
  especially 
  with 
  the 
  changes 
  and 
  altered 
  

   nutrition 
  of 
  the 
  reproductive 
  period, 
  and 
  occur 
  throughout 
  

   the 
  whole 
  extent 
  of 
  the 
  muscular 
  cavity. 
  

  

  After 
  the 
  separation 
  of 
  the 
  central 
  muscles 
  of 
  the 
  snout 
  

   the 
  conspicuous 
  hypodermic 
  fibres 
  already 
  described 
  occur 
  

   in 
  both 
  dorsal 
  and 
  ventral 
  regions. 
  Such 
  are 
  probably 
  

   elastic, 
  and 
  are 
  connected 
  functionally 
  with 
  the 
  great 
  central 
  

   vascular 
  region. 
  They 
  form 
  a 
  somewhat 
  radiate 
  arrange- 
  

   ment 
  around 
  the 
  ventral 
  space 
  inferiorly. 
  Posterior 
  to 
  the 
  

   fibres 
  just 
  mentioned 
  are 
  a 
  series 
  of 
  muscular 
  fibres, 
  which 
  

   subdivide 
  the 
  great 
  vascular 
  area 
  — 
  wide 
  in 
  the 
  middle 
  and 
  

   narrow 
  at 
  the 
  ends 
  in 
  transverse 
  section. 
  They 
  form 
  a 
  

   powerful 
  transverse 
  muscle 
  connecting 
  the 
  inferior 
  ends 
  of 
  

   the 
  external 
  chitinous 
  septa 
  (between 
  the 
  central 
  and 
  

   external 
  muscles) 
  and 
  the 
  inferior 
  borders 
  of 
  the 
  former 
  

   area. 
  The 
  space 
  is 
  further 
  divided 
  by 
  a 
  series 
  of 
  strong 
  

   fibres 
  which 
  pass 
  from 
  the 
  centre 
  and 
  sides 
  of 
  the 
  roof 
  

   downward 
  to 
  the 
  ventral 
  chamber, 
  where 
  they 
  spread 
  out, 
  

   forming 
  intersecting 
  bands. 
  As 
  the 
  central 
  muscle 
  of 
  the 
  

   snout 
  rapidly 
  disappears 
  in 
  this 
  region, 
  the 
  transverse 
  

   muscular 
  plate 
  is 
  attached 
  at 
  each 
  side 
  to 
  the 
  somewhat 
  

   angular 
  inner 
  border 
  of 
  the 
  chitinous 
  investment 
  of 
  the 
  

  

  