﻿102 
  

  

  INTEODUCTION. 
  

  

  denticulate 
  anterior 
  fold 
  leads 
  into 
  the 
  branchial 
  

   chambers 
  (&r), 
  which 
  contain 
  the 
  four 
  branchial 
  arches. 
  

  

  Fig. 
  44. 
  

  

  Transverse 
  section 
  through 
  the 
  head 
  of 
  larval 
  Pelohates 
  fuscus. 
  

   (After 
  Schulze.) 
  a. 
  Upper 
  part. 
  B. 
  Lower 
  part. 
  hr. 
  Bran- 
  

   chial 
  chambers, 
  ch. 
  Choanse. 
  I. 
  Lip. 
  m. 
  Mouth, 
  ph. 
  Pharynx. 
  

   t. 
  Tongue. 
  

  

  These 
  arches 
  bear 
  on 
  the 
  convex 
  outer 
  side 
  the 
  delicate 
  

   arborescent 
  gills, 
  and 
  on 
  the 
  concave 
  inner 
  side 
  de- 
  

   velop 
  a 
  membranous 
  septum 
  with 
  vermicular 
  perfora- 
  

   tions, 
  a 
  special 
  sifting 
  or 
  filtering 
  contrivance 
  through 
  

   which 
  the 
  water 
  absorbed 
  by 
  the 
  mouth 
  has 
  to 
  pass 
  

   before 
  reaching 
  the 
  respiratory 
  organs 
  of 
  the 
  branchial 
  

   apparatus. 
  

  

  Spiraculum. 
  — 
  The 
  water 
  is 
  expelled 
  from 
  the 
  bran- 
  

   chial 
  chambers 
  by 
  one 
  or 
  two 
  tubes 
  opening 
  by 
  one 
  

   orifice 
  in 
  all 
  European 
  Batrachians. 
  This 
  orifice 
  is 
  

   the 
  spiraculum. 
  In 
  the 
  Discoglossidse 
  two 
  tubes 
  are 
  

   present, 
  which 
  gradually 
  converge 
  towards 
  each 
  other 
  

   at 
  the 
  end 
  of 
  the 
  first 
  period 
  of 
  development, 
  as 
  sliown 
  

   on 
  Fig. 
  41, 
  p. 
  98, 
  and 
  in 
  the 
  tadpole 
  proper 
  discharge 
  

   through 
  one 
  transverse, 
  slit-like 
  or 
  crescentic 
  opening, 
  

   situated 
  in 
  the 
  middle 
  of 
  the 
  breast 
  (Fig. 
  45, 
  a, 
  sp.). 
  

   In 
  all 
  other 
  tailless 
  Batrachians 
  the 
  tube 
  is 
  single, 
  and 
  

  

  