﻿40 
  

  

  INTRODUCTION. 
  

  

  The 
  pectoral 
  arcla 
  falls 
  into 
  two 
  distinct 
  types, 
  — 
  the 
  

   arciferous 
  (Fig. 
  16, 
  a), 
  in 
  which 
  the 
  pr^coracoid 
  

  

  Fia. 
  16. 
  

  

  Pectoral 
  arch 
  and 
  fore 
  limb 
  of 
  (a) 
  Discoglossus 
  pictus 
  and 
  (b) 
  Bana 
  

   esculenta. 
  Yentral 
  view. 
  

  

  c. 
  Ooracoid. 
  

   ec. 
  Epicoracoid. 
  

   h. 
  Humerus. 
  

   ost. 
  Omosternum. 
  

   pc. 
  Pisecoracoid. 
  

  

  r. 
  Radius, 
  

   s. 
  Scapula. 
  

   ss. 
  Supra- 
  scapula. 
  

   st. 
  Sternum. 
  

   u. 
  Ulna. 
  

  

  (prsecoracoid 
  + 
  clavicle) 
  and 
  coracoid 
  are 
  widely 
  

   separated 
  from 
  each 
  other 
  distally, 
  and 
  connected 
  by 
  

   an 
  arched 
  cartilage 
  (the 
  epicoracoid), 
  the 
  right 
  usually 
  

   overlapping 
  the 
  left; 
  and 
  the 
  firmisternal 
  (Fig. 
  16, 
  b), 
  

   in 
  which 
  both 
  prsecoracoid 
  and 
  coracoid 
  nearly 
  abut 
  on 
  

   the 
  middle 
  line, 
  and 
  are 
  only 
  narrowly 
  separated 
  by 
  

   the 
  fused 
  epicoracoids. 
  The 
  latter 
  type 
  is 
  exemplified 
  

   by 
  the 
  true 
  frogs 
  (Banidm) 
  in 
  the 
  adult 
  state, 
  although 
  

  

  