﻿PLATYPTILIA 
  ISODACTYLUS. 
  195 
  

  

  6th, 
  7th, 
  and 
  8th 
  abdominal 
  segments. 
  Its 
  actual 
  position 
  is 
  on 
  the 
  

   last 
  but 
  two 
  of 
  the 
  transverse 
  ridges 
  marking 
  the 
  level 
  part 
  of 
  the 
  

   segment. 
  Of 
  these, 
  I 
  count 
  17 
  on 
  each 
  segment, 
  but 
  they 
  are 
  not 
  

   continuous, 
  and, 
  by 
  overlapping, 
  fading 
  out, 
  etc., 
  they 
  might 
  easily 
  be 
  

   counted, 
  by 
  rigid 
  ruling 
  one 
  way 
  or 
  other, 
  as 
  low 
  as 
  12, 
  or 
  as 
  many 
  as 
  

   20. 
  A 
  description 
  of 
  the 
  5th 
  abdominal 
  segment 
  gives 
  us 
  all 
  the 
  

   tubercular 
  hairs, 
  as 
  in 
  the 
  larva 
  — 
  i 
  about 
  middle 
  of 
  rough 
  part 
  of 
  

   segment, 
  behind 
  the 
  sixth 
  ridge 
  (eleventh 
  on 
  counting 
  everything 
  

   possible), 
  ii 
  just 
  behind 
  ridge 
  of 
  spines, 
  iii 
  well 
  above 
  spiracle 
  and 
  in 
  

   line 
  with 
  i, 
  though 
  there 
  is, 
  on 
  all 
  segments, 
  half-way 
  between 
  i 
  and 
  ii, 
  

   a 
  mark, 
  as 
  though 
  three 
  or 
  four 
  ridges 
  had 
  been 
  rubbed 
  down 
  with 
  a 
  

   finger 
  (supposing 
  them 
  to 
  be 
  plastic, 
  as 
  of 
  clay 
  or 
  sand) 
  , 
  which 
  interferes 
  

   with 
  following 
  the 
  ridges 
  on 
  readily. 
  In 
  front 
  of, 
  and 
  above, 
  the 
  spiracle, 
  

   is 
  a 
  minute 
  tubercular 
  point, 
  much 
  further 
  away 
  than 
  one 
  would 
  

   expect 
  to 
  see 
  the 
  accessory 
  spiracular 
  tubercle, 
  judging 
  from 
  its 
  larval 
  

   position. 
  Tubercle 
  v 
  is 
  below 
  the 
  posterior 
  margin 
  of 
  spiracle, 
  and 
  iv 
  is 
  

   below 
  and 
  behind 
  v, 
  three 
  ridges 
  above 
  spinous 
  ridge 
  ; 
  vi 
  is 
  one 
  ridge 
  

   in 
  front 
  of 
  spines, 
  and 
  vii 
  is 
  represented 
  by 
  the 
  three 
  usual 
  hairs 
  — 
  the 
  

   first 
  in 
  line 
  with 
  v, 
  the 
  second 
  (largest) 
  two 
  (or 
  three) 
  ridges 
  behind, 
  

   the 
  third, 
  one 
  ridge 
  in 
  front 
  of 
  the 
  second. 
  No 
  inner 
  (viii) 
  hair 
  

   is 
  observed. 
  On 
  the 
  6th 
  abdominal 
  segment, 
  vii 
  retains 
  only 
  one 
  hair 
  

   on 
  one 
  side 
  and 
  two 
  on 
  the 
  other, 
  there 
  is 
  also 
  a 
  minute 
  hair-point 
  

   near 
  the 
  anterior 
  border 
  of 
  segment, 
  quite 
  ventral 
  to 
  vii 
  ; 
  and 
  there 
  is 
  also 
  

   trace 
  of 
  a 
  hair-point 
  at 
  anterior 
  margin, 
  between 
  ii 
  and 
  iii. 
  The 
  

   spinous 
  ridge 
  is 
  very 
  similar 
  on 
  the 
  4th, 
  5th 
  and 
  6th 
  abdominal 
  

   segments. 
  The 
  largest 
  spines, 
  four 
  ventrally 
  on 
  either 
  side, 
  are 
  

   sharp, 
  and 
  triangular, 
  and 
  pointed 
  backwards 
  ; 
  one 
  ventral 
  to 
  v, 
  two, 
  

   one 
  on 
  either 
  side 
  of, 
  and 
  close 
  to, 
  vi, 
  and 
  one 
  just 
  posterior 
  to 
  vii 
  ; 
  the 
  

   first 
  and 
  last 
  of 
  these 
  are 
  longest. 
  Immediately 
  ventral 
  to 
  the 
  last 
  is 
  

   a 
  hollow, 
  with 
  thick 
  raised 
  anterior 
  ridge, 
  that, 
  though 
  almost 
  too 
  

   posterior, 
  is 
  almost 
  certainly 
  scar 
  of 
  proleg, 
  as 
  there 
  is 
  no 
  other, 
  and 
  

   it 
  does 
  not 
  occur 
  on 
  the 
  7th 
  abdominal 
  segment. 
  There 
  is 
  a 
  very 
  similar 
  

   mark, 
  still 
  in 
  line 
  of 
  spinous 
  ridge, 
  below 
  the 
  spiracles, 
  but 
  it 
  is 
  less 
  

   of 
  a 
  hollow 
  or 
  pocket, 
  and 
  the 
  raised 
  margin 
  (ridge) 
  is 
  behind 
  it. 
  

   Dorsal 
  of 
  this, 
  the 
  ridge 
  is 
  merely 
  a 
  line, 
  except 
  just 
  below 
  ii, 
  where 
  

   there 
  is 
  a 
  low 
  spine 
  ; 
  above 
  ii 
  the 
  ridge 
  is 
  well 
  marked, 
  with 
  thinner 
  

   portion 
  in 
  front 
  of 
  it. 
  The 
  17 
  (12, 
  or 
  20, 
  as 
  may 
  be) 
  ridges, 
  are 
  about 
  

   twice 
  their 
  own 
  widths 
  (and 
  heights) 
  apart, 
  and, 
  whilst 
  their 
  summits 
  

   are 
  fairly 
  transverse 
  lines, 
  their 
  margins 
  are 
  very 
  irregular; 
  regarding 
  

   them 
  as 
  hills, 
  their 
  flanks 
  have 
  many 
  small 
  subsidiary 
  ridges 
  running- 
  

   down 
  into 
  the 
  plain. 
  The 
  finer 
  sculpturing 
  consists 
  of 
  numerous 
  

   minute 
  pits 
  (3 
  or 
  4 
  in 
  width 
  of 
  a 
  valley), 
  circular, 
  and 
  well 
  separate 
  

   from 
  each 
  other 
  ; 
  to 
  be 
  like 
  those 
  of 
  FredeHcina 
  calodactyla 
  (zetterstedtii\ 
  s 
  

   they 
  would 
  have 
  to 
  enlarge 
  to 
  twice 
  their 
  size, 
  and 
  diminish 
  the 
  plain 
  

   on 
  which 
  they 
  are, 
  by 
  the 
  consequent 
  encroachment, 
  but 
  they 
  are, 
  

   perhaps, 
  not 
  so 
  regularly 
  placed 
  as 
  in 
  that 
  species. 
  There 
  is. 
  however 
  

   quite 
  a 
  different 
  sculpturing 
  in 
  places, 
  and, 
  all 
  along 
  the 
  anterior 
  

   margin 
  (except 
  just 
  dorsally 
  and 
  in 
  front 
  of 
  the 
  spiracle), 
  and 
  along 
  the 
  

   posterior 
  margin 
  ventral 
  to 
  v, 
  and 
  the 
  whole 
  width 
  of 
  the 
  segment 
  

   ventrally, 
  nearly 
  out 
  to 
  vii, 
  there 
  are 
  no 
  pits, 
  but 
  extremely 
  sharp 
  skin- 
  

   points, 
  directed 
  backwards, 
  about 
  nine 
  in 
  width 
  o( 
  a 
  ridge 
  and 
  valley 
  ; 
  

   on 
  the 
  7th 
  abdominal, 
  these 
  skin-points 
  invade 
  most 
  of 
  the 
  segment. 
  

   Tho 
  spiracles 
  are 
  well-marked 
  circles 
  about 
  0*08mm. 
  in 
  diameter, 
  bhat 
  

  

  