﻿544 
  REPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [56] 
  

  

  tically 
  firm 
  in 
  character, 
  but 
  globular 
  instead 
  of 
  flattened 
  and 
  oval 
  or 
  

   elongated, 
  as 
  in 
  the 
  ova 
  of 
  Ganoids, 
  Amphibians, 
  and 
  Elasmobranchs. 
  

  

  The 
  muscular 
  bundles 
  M 
  M, 
  cut 
  through 
  at 
  several 
  points, 
  actuate 
  or 
  

   belong 
  to 
  the 
  pharyngeal, 
  branchial, 
  submaxillary, 
  and 
  hyoid 
  regions 
  

   of 
  the 
  head. 
  The 
  intestine 
  7, 
  oesophagus 
  Oe, 
  and 
  air-bladder 
  Ab, 
  are 
  

   cut 
  through 
  in 
  the 
  middle 
  line 
  in 
  the 
  section 
  here 
  represented. 
  The 
  

   anterior 
  part 
  of 
  the 
  chorda 
  Ch 
  has 
  also 
  been 
  divided 
  in 
  the 
  middle 
  line, 
  

   and 
  the 
  rudiments 
  of 
  the 
  three 
  anterior 
  centra 
  x 
  x 
  x 
  are 
  seen 
  to 
  be 
  

   shorter 
  than 
  those 
  which 
  follow. 
  Two 
  of 
  these 
  centra 
  eventually 
  coa- 
  

   lesce 
  with 
  each 
  other, 
  and 
  with 
  the 
  fourth 
  and 
  fifth 
  form 
  the 
  co-ossified 
  

   anterior 
  segment 
  composed 
  of 
  four 
  vertebral 
  bodies 
  in 
  the 
  spinal 
  col- 
  

   umn 
  of 
  the 
  adult. 
  Some 
  of 
  the 
  lateral 
  processes 
  and 
  parts 
  of 
  the 
  neural 
  

   arches 
  of 
  these 
  co-ossified 
  vertebras, 
  especially 
  the 
  first, 
  second, 
  and 
  third, 
  

   give 
  rise, 
  according 
  to 
  McMurrich, 
  to 
  the 
  series 
  of 
  ossicles 
  by 
  which 
  the 
  

   air-bladder 
  and 
  auditory 
  apparatus 
  are 
  brought 
  into 
  intimate 
  physiolog- 
  

   ical 
  relations 
  with 
  each 
  other. 
  

  

  The 
  development 
  of 
  the 
  shoulder 
  girdle 
  is 
  remarkable 
  from 
  the 
  cir- 
  

   cumstance 
  that 
  the 
  coracoid 
  portion 
  originally 
  laid 
  down 
  in 
  cartilage 
  is 
  

   excessively 
  developed, 
  extending 
  downward 
  as 
  a 
  great 
  flat 
  cartilagin- 
  

   ous 
  blade, 
  Cor, 
  from 
  the 
  base 
  of 
  the 
  pectoral 
  fin, 
  as 
  shown 
  in 
  fig. 
  173. 
  

   In 
  front 
  of 
  the 
  coracoid 
  the 
  membranous 
  basis 
  of 
  a 
  parostosis 
  is 
  already 
  

   formed 
  ; 
  this 
  is 
  clearly 
  the 
  rudiment 
  of 
  the 
  element 
  termed 
  the 
  clavicle 
  

   by 
  Huxley 
  and 
  Parker 
  in 
  other 
  osseous 
  fishes. 
  The 
  scapular 
  portion 
  8c 
  

   of 
  this 
  cartilage 
  is 
  small, 
  and 
  is 
  prolonged 
  anteriorly 
  into 
  two 
  cornua, 
  

   between 
  which 
  there 
  is 
  a 
  well-marked 
  glenal 
  fossa 
  in 
  which 
  the 
  basal 
  

   ends 
  of 
  the 
  pectoral 
  rays 
  are 
  lodged 
  5 
  two 
  nodules 
  of 
  cartilage, 
  1, 
  2, 
  rep- 
  

   resent 
  with 
  some 
  doubt, 
  the 
  actinosts. 
  The 
  metapterygial 
  actinost, 
  if 
  

   it 
  be 
  such, 
  is 
  the 
  larger 
  of 
  the 
  two 
  and 
  the 
  most 
  anterior, 
  forming, 
  in 
  

   fact, 
  the 
  basal 
  part 
  of 
  the 
  first 
  pectoral 
  ray 
  which 
  eventually 
  becomes 
  

   developed 
  as 
  a 
  strong 
  spine. 
  This 
  relation 
  of 
  these 
  nodules 
  to 
  the 
  rays 
  

   would 
  indicate 
  that 
  they 
  were 
  actinophores 
  and 
  that 
  therefore 
  true 
  ac- 
  

   tinosts 
  are 
  not 
  developed 
  in 
  Ictalurus. 
  

  

  The 
  nomenclature 
  followed 
  above 
  in 
  naming 
  the 
  choudrified 
  parts 
  of 
  

   the 
  shoulder 
  girdle 
  is 
  that 
  used 
  by 
  Huxley. 
  Dr. 
  Gill, 
  however, 
  regards 
  

   the 
  whole 
  cartilaginous 
  plate 
  8c 
  and 
  Cor 
  as 
  scapula, 
  but 
  there 
  is 
  no 
  sub- 
  

   division 
  of 
  this 
  plate 
  into 
  hypercoracoid 
  and 
  hypocoracoid 
  elements, 
  but 
  

   it 
  forms 
  a 
  solid 
  piece, 
  the 
  upper 
  part 
  of 
  which 
  alone 
  gives 
  support 
  to 
  

   the 
  pectoral 
  and 
  the 
  reduced 
  actinosts, 
  or 
  perhaps 
  rather 
  actinophores, 
  

   already 
  described. 
  

  

  