﻿422 
  Prof. 
  M'Intosh 
  on 
  the 
  

  

  compact 
  and 
  granular 
  than 
  the 
  rest) 
  are 
  directed 
  from 
  each 
  

   side 
  downward 
  and 
  inward, 
  then 
  outward 
  toward 
  the 
  narrow 
  

   part 
  under 
  the 
  external 
  muscle. 
  The 
  lateral 
  division 
  has 
  the 
  

   form 
  of 
  a 
  lanceolate 
  process 
  on 
  each 
  side, 
  the 
  wide 
  base 
  

   abutting 
  on 
  the 
  convex 
  margin 
  of 
  the 
  muscular 
  compartment, 
  

   from 
  which 
  a 
  chitinous 
  plate 
  proceeds 
  outward 
  along 
  the 
  

   central 
  line. 
  The 
  hypodermic 
  tissue 
  is 
  lax 
  at 
  the 
  basal 
  or 
  

   wide 
  portion, 
  and 
  becomes 
  more 
  granular 
  toward 
  the 
  free 
  

   margin 
  in 
  the 
  preparations. 
  In 
  transverse 
  vertical 
  section 
  

   the 
  soft 
  connective-tissue 
  fibres 
  extend 
  from 
  the 
  central 
  

   chitinous 
  plate 
  upward 
  and 
  outward 
  dorsally 
  and 
  downward 
  

   and 
  outward 
  ventrally, 
  the 
  whole 
  having 
  the 
  aspect 
  of 
  a 
  leaf 
  

   with 
  its 
  midrib 
  and 
  veins. 
  At 
  the 
  external 
  margin 
  a 
  fan-like 
  

   arrangement 
  of 
  the 
  fibres 
  occurs. 
  In 
  vertical 
  longitudinal 
  

   sections 
  a 
  similar 
  appearance 
  is 
  found, 
  though 
  in 
  this 
  case 
  

   the 
  leaf 
  is 
  almost 
  linear. 
  No 
  trace 
  of 
  capillaries 
  occurs 
  in 
  

   the 
  lateral 
  or 
  other 
  hypoderm 
  of 
  the 
  snout. 
  

  

  Proceeding 
  backward, 
  the 
  ventral 
  hypodermic 
  tissue 
  

   increases 
  in 
  bulk, 
  and 
  its 
  structure 
  becomes 
  more 
  distinctly 
  

   fibrous, 
  and 
  by-and-by 
  it 
  passes 
  upward 
  so 
  as 
  to 
  separate 
  the 
  

   median 
  muscular 
  spaces, 
  as 
  in 
  front. 
  In 
  the 
  large 
  area 
  

   formed 
  between 
  the 
  latter 
  spaces 
  the 
  fibres 
  of 
  the 
  hypoderm 
  

   follow 
  definite 
  courses. 
  Dorsally 
  they 
  sweep 
  from 
  the 
  

   cuticular 
  margin 
  downward 
  and 
  outward 
  to 
  the 
  inner 
  mus- 
  

   cular 
  compartment, 
  and 
  a 
  few 
  of 
  the 
  inner 
  fibres 
  pass 
  to 
  the 
  

   chamber 
  for 
  the 
  blood-vessels 
  beneath. 
  Ventrally 
  they 
  are 
  

   directed 
  from 
  the 
  latter 
  and 
  the 
  chitinous 
  process 
  externally, 
  

   downward 
  and 
  inward 
  to 
  the 
  cuticle. 
  Such 
  fibres 
  would 
  aid 
  

   in 
  retaining 
  the 
  muscular 
  chambers 
  in 
  position 
  during 
  the 
  

   varied 
  movements 
  of 
  the 
  snout 
  and 
  give 
  firmness 
  to 
  the 
  

   region. 
  Still 
  increasing 
  in 
  extent, 
  the 
  ventral 
  hypoderm 
  

   then 
  presents 
  a 
  small 
  oblong 
  area 
  above 
  the 
  cuticle, 
  in 
  the 
  

   median 
  line. 
  This 
  is 
  the 
  precursor 
  of 
  the 
  great 
  transverse 
  

   space 
  immediately 
  behind. 
  Above 
  the 
  latter 
  space 
  the 
  hypo- 
  

   derm 
  is 
  vertically 
  streaked 
  by 
  somewhat 
  isolated 
  bands 
  of 
  

   fibres, 
  and 
  numerous 
  granular 
  cells 
  occur 
  all 
  over, 
  especially 
  

   in 
  the 
  more 
  opaque 
  central 
  region 
  superiorly. 
  When 
  the 
  

   latter 
  has 
  reached 
  its 
  full 
  development 
  the 
  large 
  dorsal 
  area 
  

   with 
  its 
  dense 
  covering 
  of 
  cuticle 
  is 
  divisible 
  into 
  two 
  parts 
  — 
  

   an 
  upper 
  cellulo-granular 
  and 
  an 
  inferior 
  fibro-granular 
  

   region 
  — 
  stretching 
  from 
  side 
  to 
  side 
  between 
  the 
  remnants 
  

   of 
  the 
  central 
  longitudinal 
  muscle. 
  The 
  fibres 
  are 
  chiefly 
  

   transverse 
  in 
  direction, 
  though 
  some 
  (apparently 
  pertaining 
  

   to 
  the 
  vertical 
  series 
  previously 
  mentioned) 
  pass 
  at 
  right 
  

   angles 
  to 
  these 
  from 
  above 
  downward 
  to 
  the 
  roof 
  of 
  the 
  

   space. 
  The 
  ventral 
  hypoderm 
  is 
  now 
  much 
  more 
  lax 
  and 
  

  

  