﻿580 
  EEPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [92] 
  

  

  EXPLANATION 
  OF 
  PLATE 
  XVIII. 
  

  

  Clupea 
  sapidissima. 
  (The 
  Common 
  Sluid.) 
  

  

  Figs. 
  122 
  and 
  123. 
  Two 
  views 
  of 
  unhatehed 
  embryos 
  of 
  nearly 
  the 
  same 
  age, 
  which 
  

   developed 
  in 
  a 
  temperature 
  of 
  45° 
  F., 
  producing 
  distortions 
  of 
  the 
  tail 
  andnoto- 
  

   chord. 
  From 
  photographs. 
  

  

  Fig. 
  124. 
  Egg 
  which 
  was 
  impregnated 
  at 
  a 
  normal 
  temperature 
  and 
  which 
  developed 
  

   the 
  blastodisk 
  in 
  a 
  normal 
  way, 
  but 
  subsequently, 
  exposed 
  to 
  a 
  temperature 
  of 
  

   45° 
  F., 
  the 
  blastodisk 
  was 
  distorted 
  as 
  here 
  shown. 
  From 
  a 
  photograph. 
  

  

  Fig. 
  125. 
  Transparent 
  view 
  from 
  below 
  of 
  front 
  eud 
  of 
  an 
  embryo 
  at 
  about 
  the 
  time 
  

   the 
  mouth 
  is 
  formed. 
  

  

  Fig. 
  126. 
  An 
  egg- 
  envelope 
  with 
  its 
  contained 
  embryo, 
  forty-four 
  hours 
  after 
  impreg- 
  

   nation, 
  viewed 
  as 
  a 
  transparent 
  object. 
  

  

  Fig. 
  127. 
  An 
  egg-envelope 
  with 
  its 
  contained 
  embryo 
  at 
  the 
  beginning 
  of 
  the 
  third 
  

   day 
  of 
  development. 
  From 
  a 
  photograph. 
  

  

  Fig. 
  128. 
  Dorsal 
  view 
  of 
  the 
  front 
  part 
  of 
  an 
  embryo 
  at 
  the 
  time 
  the 
  pectoral 
  fins 
  

   are 
  beginning 
  to 
  appear 
  as 
  lateral 
  folds. 
  

  

  Fig. 
  129. 
  Diagrammatic 
  cross-section 
  through 
  the 
  pectoral 
  fin 
  of 
  an 
  embryo, 
  to 
  illus- 
  

   trate 
  the 
  way 
  in 
  which 
  the 
  mesoblast 
  is 
  proliferated 
  into 
  the 
  integumentary 
  fin- 
  

   fold. 
  

  

  Fig. 
  130. 
  Transverse 
  profile 
  view 
  of 
  the 
  dorsal 
  pectoral 
  region 
  of 
  an 
  embryo 
  in 
  the 
  

   stage 
  represented 
  in 
  fig. 
  128. 
  

  

  