﻿SKELETON. 
  

  

  33 
  

  

  y. 
  Skeleton. 
  

  

  The 
  skull 
  is 
  more 
  or 
  less 
  strongly 
  depressed, 
  and 
  

   remarkable 
  for 
  the 
  extremely 
  large 
  orbits 
  and 
  the 
  

   reduction 
  in 
  the 
  number 
  of 
  elements. 
  We 
  have 
  to 
  

   distinguish 
  between 
  the 
  chondrocranmm, 
  or 
  primitive 
  

   skull 
  — 
  consisting 
  mainly 
  of 
  cartilage 
  with 
  a 
  few 
  ossified 
  

   parts, 
  with 
  a 
  large 
  fontanelle 
  or 
  membranous 
  space 
  in 
  

   the 
  interorbital 
  region, 
  and 
  foramina 
  for 
  the 
  exit 
  of 
  

   the 
  cranial 
  nerves, 
  — 
  and 
  the 
  membrane 
  hones, 
  which 
  

   may 
  be 
  removed 
  by 
  maceration. 
  

  

  The 
  ossified 
  parts 
  of 
  the 
  chondrocranium,or 
  cartilage 
  

   bones 
  (Fig. 
  11), 
  are 
  the 
  ethmoid 
  or 
  sphenethmoid, 
  form- 
  

   ing 
  a 
  ring 
  round 
  the 
  anterior 
  part 
  of 
  the 
  brain- 
  case, 
  the 
  

  

  Fig. 
  1L 
  

  

  Ohondrocranium 
  

   A. 
  Upper 
  view. 
  

  

  c. 
  Brain-case. 
  

  

  e. 
  Ethmoid. 
  

   eo. 
  ExoccipitaL 
  

   fe. 
  Fontanelle. 
  

   /m. 
  Foramen 
  magnum. 
  

   fo. 
  Optic 
  foramen. 
  

   ft. 
  Trigeminal 
  foramen. 
  

  

  oi 
  Rana 
  esculenta. 
  

   B. 
  Lower 
  view. 
  

   j. 
  Jugal. 
  

  

  I. 
  Lachrymal 
  process. 
  

   n. 
  Nasal 
  capsule. 
  

   pr. 
  Prootic. 
  

   pt. 
  Pterygoid 
  branch. 
  

   sp. 
  Suspensorium. 
  

  

  (paired) 
  prootic 
  behind 
  the 
  orbit, 
  the 
  (paired) 
  exoccipital 
  

   on 
  each 
  side 
  of 
  the 
  foramen 
  magnum, 
  forming 
  the 
  

   (paired) 
  occipital 
  condyle 
  articulating 
  with 
  the 
  first 
  ver- 
  

   tebra, 
  and 
  a 
  styliform 
  jugal 
  connecting 
  the 
  cartila- 
  

   ginous 
  suspensorium 
  of 
  the 
  mandible 
  or 
  the 
  ossified 
  

   quadrate 
  with 
  the 
  maxillary. 
  

  

  

  

  