﻿680 
  EEPORT 
  OF 
  COMMISSIONER 
  OF 
  FISH 
  AND 
  FISHERIES. 
  [70] 
  

  

  of 
  the 
  first 
  and 
  third 
  as 
  in 
  the 
  allied 
  genera, 
  and 
  the 
  pleura 
  of 
  the 
  

   third, 
  fourth, 
  and 
  fifth 
  somites 
  are 
  evenly 
  and 
  similarly 
  rounded 
  pos- 
  

   teriorly. 
  

  

  In 
  Gr. 
  O. 
  Sars's 
  elaborate 
  and 
  very 
  fully 
  illustrated 
  work 
  on 
  the 
  Crus- 
  

   tacea 
  of 
  the 
  Norwegian 
  North-Atlantic 
  expedition, 
  which 
  I 
  had 
  not 
  seen 
  

   when 
  the 
  above 
  was 
  written, 
  the 
  telson 
  of 
  II. 
  glacialis 
  is 
  described 
  and 
  

   figured 
  as 
  armed 
  at 
  the 
  tip 
  with 
  seven 
  slender 
  spines, 
  a 
  pair 
  of 
  long 
  

   lateral 
  separated 
  by 
  five 
  much 
  smaller 
  ones 
  ; 
  while 
  in 
  the 
  female 
  from 
  

   station 
  2039, 
  the 
  only 
  one 
  of 
  the 
  Albatross 
  specimens 
  in 
  which 
  the 
  tel- 
  

   son 
  is 
  perfect, 
  there 
  are 
  only 
  six 
  spines, 
  there 
  being 
  no 
  odd 
  median 
  one, 
  

   and 
  the 
  same 
  is 
  true 
  of 
  the 
  two 
  specimens 
  from 
  the 
  Faroe 
  Channel. 
  

  

  Partial 
  measurements 
  of 
  two 
  specimens 
  of 
  H. 
  glacialis 
  are 
  given 
  under 
  

   the 
  next 
  species. 
  

  

  Hymenodora 
  gracilis, 
  sp. 
  nov. 
  

  

  (Plate 
  XII, 
  Fig. 
  6.) 
  

  

  This 
  species 
  is 
  apparently 
  somewhat 
  smaller 
  than 
  H. 
  glacialis, 
  and 
  is 
  

   distinguished 
  by 
  its 
  more 
  slender 
  form 
  and 
  longer 
  and 
  more 
  slender 
  ros- 
  

   trum, 
  which 
  is 
  prolonged 
  in 
  a 
  slender, 
  unarmed 
  tip, 
  reaching 
  as 
  far 
  for- 
  

   ward 
  as 
  the 
  tips 
  of 
  the 
  eyes. 
  The 
  antennal 
  scale 
  is 
  apparently 
  consid- 
  

   erably 
  narrower. 
  In 
  the 
  only 
  specimen 
  in 
  which 
  the 
  tip 
  of 
  the 
  telson 
  is 
  

   perfect, 
  the 
  male 
  from 
  station 
  2036, 
  it 
  is 
  armed 
  with 
  only 
  four 
  spines, 
  

   there 
  being 
  only 
  two 
  between 
  the 
  long 
  lateral 
  spines. 
  The 
  most 
  re- 
  

   markable 
  difference, 
  however, 
  is 
  in 
  the 
  first 
  gnathopods, 
  which, 
  as 
  al- 
  

   ready 
  remarked, 
  bear 
  distinct 
  podo 
  branchiae. 
  In 
  the 
  larger 
  specimens 
  

   these 
  branchiae 
  are 
  conspicuous 
  and 
  composed 
  of 
  several 
  lamellae 
  each, 
  

   being 
  nearly 
  as 
  large 
  in 
  proportion 
  to 
  the 
  size 
  of 
  the 
  animal 
  as 
  in 
  Men- 
  

   ingodora 
  mollis; 
  but 
  in 
  some 
  of 
  the 
  smaller 
  specimens 
  they 
  are 
  repre- 
  

   sented 
  by 
  only 
  one 
  or 
  two 
  small 
  lamellae 
  attached 
  near 
  the 
  base 
  of 
  the 
  

   epipod, 
  and 
  are 
  very 
  easily 
  overlooked. 
  There 
  are 
  well-developed 
  pod- 
  

   obranchiae 
  at 
  the 
  bases 
  of 
  the 
  first 
  gnathopods 
  in 
  all 
  the 
  species 
  of 
  the 
  

   allied 
  genera 
  known 
  to 
  me, 
  Acanthephyra, 
  Epliyrina, 
  Notostomus, 
  and 
  

   Meningodora, 
  and 
  I 
  had 
  regarded 
  their 
  absence 
  as 
  one 
  of 
  the 
  best 
  gen- 
  

   eric 
  characters 
  of 
  Hymenodora, 
  but 
  their 
  occurrence 
  and 
  variability 
  in 
  

   a 
  species 
  so 
  very 
  closely 
  allied 
  to 
  the 
  typical 
  species 
  of 
  the 
  genus 
  shows 
  

   that 
  they 
  are 
  not 
  always 
  of 
  generic 
  importance. 
  The 
  two 
  species 
  of 
  

   Hymenodora 
  still 
  differ, 
  however, 
  from 
  the 
  species 
  of 
  the 
  allied 
  genera 
  

   above-named 
  in 
  the 
  form 
  of 
  the 
  protognath 
  of 
  the 
  second 
  maxilla 
  and 
  in 
  

   the 
  number 
  of 
  segments 
  in 
  the 
  endopod 
  of 
  the 
  maxilliped, 
  characters 
  

   which, 
  for 
  the 
  present 
  at 
  least, 
  may 
  be 
  regarded 
  as 
  of 
  generic 
  value. 
  

  

  