﻿30 
  

  

  ACTINOPTERTGII. 
  

  

  few 
  of 
  these 
  arches 
  are 
  shown 
  of 
  the 
  natural 
  size 
  in 
  

   PI. 
  I. 
  fig. 
  4. 
  Egerton 
  Coll. 
  

  

  P. 
  3362. 
  Imperfect 
  head, 
  pectoral 
  arch 
  with 
  fins, 
  and 
  some 
  of 
  the 
  

   anterior 
  vertebral 
  arches, 
  described 
  and 
  figured 
  by 
  Eger- 
  

   ton, 
  loc. 
  tit. 
  p. 
  873, 
  pi. 
  lxix. 
  Th'e 
  portion 
  of 
  axial 
  

   skeleton 
  behind 
  the 
  head 
  is 
  not 
  accurately 
  drawn, 
  there 
  

   being 
  only 
  a 
  single 
  series 
  of 
  long 
  slender 
  spines 
  loosely 
  

   apposed 
  to 
  their 
  more 
  robust 
  neural 
  arches. 
  As 
  remarked 
  

   by 
  Traquair, 
  the 
  maxilla 
  is 
  interpreted 
  by 
  Egerton 
  as 
  

   mandible 
  (numbered 
  32), 
  the 
  palatine 
  (or 
  ectopterygoid) 
  

   as 
  maxilla 
  (21), 
  the 
  suborbital 
  as 
  premaxilla 
  (22), 
  and 
  the 
  

   jugal 
  as 
  coalesced 
  mesotympanic 
  and 
  hypotympanic 
  (28 
  d). 
  

  

  Ennishillen 
  Coll. 
  

  

  , 
  seen 
  obliquely 
  from 
  below 
  (after 
  

   [No. 
  P. 
  2048.] 
  

  

  Head 
  of 
  Chondrosteus 
  aoi% 
  

  

  Traquair). 
  

   Lettering 
  of 
  figs. 
  5 
  and 
  6 
  : 
  — 
  

  

  ac/., 
  angular 
  ; 
  br., 
  branchiostegal 
  rays 
  ; 
  cb., 
  cerato-branchial 
  ; 
  c.h., 
  cerato-hyal 
  ; 
  

   cl., 
  clavicle 
  ; 
  d., 
  dentary 
  ; 
  /., 
  frontal 
  ; 
  km., 
  hyomandibular 
  ; 
  on.pt., 
  mesopterygoid 
  ; 
  

   once., 
  maxilla 
  ; 
  op., 
  operculum 
  ; 
  pa.sph., 
  parasphenoid 
  ; 
  pt., 
  palatine 
  ; 
  pt.f., 
  

   post-frontal 
  ; 
  s.cl., 
  supraclavicle 
  ; 
  s.o., 
  suborbital 
  ; 
  s.op., 
  suboperculum 
  ; 
  sq. 
  f 
  

   squamosal. 
  

  

  