﻿Report 
  of 
  tee 
  State 
  Geologist. 
  

  

  357 
  

  

  sented 
  by 
  continuous 
  lines, 
  probable 
  or 
  possible 
  sutures 
  by 
  dotted 
  

   lines, 
  and 
  the 
  sensory 
  canals 
  by 
  broken 
  lines. 
  To 
  explain 
  this 
  

   figure, 
  a 
  copy 
  of 
  the 
  restoration 
  of 
  the 
  composition 
  of 
  the 
  

   cranium 
  of 
  Coccosteus 
  decipiens, 
  Agassiz, 
  as 
  made 
  out 
  by 
  Tra- 
  

   qttair 
  * 
  and 
  a 
  portion 
  of 
  a 
  side 
  view 
  given 
  by 
  Lydekker,! 
  are 
  

   also 
  introduced, 
  the 
  lines 
  having 
  the 
  same 
  meaning 
  in 
  all 
  the 
  

   figures 
  and 
  the 
  lettering 
  of 
  the 
  plates 
  being 
  the 
  same. 
  

  

  Fig. 
  1 
  —Restoration 
  of 
  the 
  top 
  of 
  the 
  head 
  in 
  

   Coccosteus 
  decipiens. 
  (Traquair.) 
  

  

  Fig. 
  2 
  — 
  Right 
  iateral 
  aspect 
  of 
  the 
  head 
  

   (Lydekker.) 
  

  

  The 
  proportions 
  of 
  this 
  specimen 
  compared 
  with 
  those 
  of 
  the 
  

   best 
  known 
  representatives 
  of 
  the 
  genus, 
  G 
  decipiens, 
  Agassiz, 
  

   and 
  G 
  inflatus, 
  von 
  Koenen,+ 
  are 
  large, 
  but 
  compare 
  well 
  in 
  size 
  

   to 
  that 
  described 
  by-WniTEAVEs 
  as 
  G 
  acadica.% 
  

  

  Sensory 
  canals. 
  These 
  conspicuous 
  features 
  of 
  the 
  cranium 
  

   converge 
  near 
  the 
  center 
  of 
  the 
  shield 
  Justin 
  front 
  of 
  the 
  median 
  

   occipital 
  plate 
  (m. 
  o.). 
  They 
  do 
  not 
  come 
  in 
  contact 
  at 
  this 
  place, 
  

   either 
  with 
  one 
  another 
  or 
  with 
  the 
  true 
  sutures. 
  The 
  most 
  dis- 
  

   tinct 
  pair 
  makes 
  a 
  double 
  curve 
  anteriorly 
  and 
  becomes 
  contin- 
  

   uous 
  at 
  the 
  anterior 
  extremity 
  of 
  the 
  specimen, 
  inclosing 
  a 
  

   clavate 
  area. 
  These 
  canals 
  must 
  have 
  been 
  very 
  deep 
  and 
  hence 
  

   formed 
  lines 
  of 
  weakness 
  in 
  the 
  shield 
  when 
  under 
  compression, 
  

  

  ♦Geological 
  Magazine, 
  Dee. 
  Ill, 
  vol. 
  VI, 
  pp. 
  1-8, 
  pi. 
  1, 
  1889; 
  Proc. 
  Roy. 
  Phys. 
  Soc. 
  Ediab. 
  

   Vol. 
  X, 
  pp. 
  47-57, 
  pi. 
  3. 
  

  

  t 
  Nicholson 
  and 
  Lydexker, 
  Manual 
  of 
  Palaeontology, 
  vol. 
  II, 
  p. 
  965, 
  1889. 
  

  

  X 
  The 
  writer 
  had 
  the 
  opportunity, 
  some 
  years 
  ago, 
  of 
  studying 
  and 
  making 
  sketches 
  of 
  the 
  

   original 
  of 
  this 
  species, 
  from 
  the 
  Devonian 
  of 
  Bicken, 
  though 
  von 
  Koenen's 
  paper 
  (Beitr. 
  zur 
  

   Kenntniss 
  der 
  Piacodermen 
  Fische, 
  1883) 
  is 
  not 
  now 
  accessible 
  to 
  him. 
  The 
  restored 
  figure 
  of 
  

   this 
  species 
  is, 
  however, 
  reproduced 
  in 
  Zittei/s 
  Handbuch 
  der 
  Palaontologie 
  (vol. 
  m, 
  p. 
  160, 
  

   fig, 
  167, 
  1890). 
  

  

  § 
  Canadian 
  Naturalist, 
  vol. 
  X, 
  p. 
  94, 
  1881, 
  and 
  Trans. 
  Roy. 
  Soc. 
  Canada, 
  vol. 
  VI, 
  p. 
  93, 
  pi. 
  IX, 
  

  

  