﻿On 
  Parasitic 
  Castration 
  in 
  Lumbricus 
  herculeus. 
  335 
  

  

  Family 
  2. 
  Exocoetidae. 
  

  

  Pnemaxillaries 
  with 
  straight 
  transverse 
  anterior 
  margin 
  ; 
  

   maxillaries 
  free 
  from 
  or 
  merely 
  adherent 
  to 
  prsemaxillaries 
  ; 
  

   teeth 
  in 
  jaws 
  minute, 
  villiform 
  ; 
  third 
  upper 
  pharyngeals 
  

   simply 
  coalescent, 
  the 
  plate 
  readily 
  separating 
  into 
  its 
  two 
  

   components. 
  Vertebrae 
  44 
  to 
  52 
  ; 
  most 
  of 
  the 
  parapophyses 
  

   directed 
  somewhat 
  downwards 
  aud 
  forwards. 
  Pectoral 
  fins 
  

   large. 
  . 
  

  

  Genera: 
  Exocoetus, 
  Halocypselus, 
  Parexocoetus, 
  Fodiator. 
  

  

  EXPLANATION 
  OF 
  PLATE 
  IX. 
  

  

  Dentigerous 
  pharyngeal 
  bones 
  of: 
  A. 
  Exocoetus 
  Uneafus; 
  B. 
  Hemi- 
  

   rhamphus 
  intermedins; 
  C. 
  Xenentodon 
  cancila 
  ; 
  D. 
  Tylosurus 
  

   acus 
  ; 
  E. 
  Belone 
  belone 
  ; 
  F. 
  Scombresox 
  saurus. 
  The 
  second, 
  

   third, 
  aud 
  fourth 
  upper 
  pharyngeals 
  are 
  numbered. 
  

  

  XXXVII. 
  — 
  Note 
  on 
  Parasitic 
  Castration 
  in 
  the 
  Earthworm 
  

   Lumbricus 
  herculeus. 
  By 
  Igerna 
  B. 
  J. 
  Sollas, 
  B.Sc, 
  

   Newnham 
  College, 
  Cambridge. 
  

  

  All 
  observations 
  on 
  parasitic 
  castration 
  have 
  acquired 
  fresh 
  

   interest 
  since 
  the 
  publication 
  of 
  Mr. 
  Geoffrey 
  Smith's 
  work 
  on 
  

   the 
  experimental 
  analysis 
  of 
  sex 
  (3). 
  Also, 
  so 
  far 
  as 
  I 
  know, 
  

   no 
  case 
  of 
  parasitic 
  castration 
  of 
  a 
  hermaphrodite 
  animal 
  is 
  at 
  

   present 
  on 
  record. 
  

  

  The 
  castration 
  described 
  in 
  this 
  note 
  attracted 
  my 
  attention 
  

   in 
  February 
  1910, 
  when 
  I 
  found 
  that 
  of 
  ten 
  full-sized 
  earth- 
  

   worms 
  provided 
  for 
  demonstration 
  purposes 
  five 
  possessed 
  

   either 
  no 
  clitellum 
  or 
  an 
  imperfectly 
  developed 
  clitellum, 
  and 
  

   in 
  the 
  abnormal 
  individuals 
  the 
  seminal 
  vesicles 
  were 
  either 
  

   small 
  and 
  contained 
  no 
  sperm 
  at 
  any 
  stage 
  of 
  development, 
  

   or 
  they 
  were 
  more 
  or 
  less 
  normal 
  as 
  to 
  size, 
  but 
  contained 
  

   chiefly 
  immature 
  stages 
  of 
  sperm-cells. 
  The 
  spermatheca3 
  

   were 
  empty 
  ; 
  the 
  ovaries 
  were 
  normal. 
  In 
  those 
  worms 
  in 
  

   • 
  which 
  the 
  degeneration 
  of 
  the 
  seminal 
  vesicles 
  was 
  most 
  com- 
  

   plete 
  not 
  only 
  was 
  there 
  no 
  trace 
  of 
  clitellum, 
  but 
  the 
  lips 
  of 
  

   the 
  male 
  duct 
  were 
  not 
  tumid 
  and 
  the 
  genital 
  chsetse 
  were 
  not 
  

   more 
  prominent 
  than 
  the 
  rest. 
  Further 
  batches 
  of 
  worms 
  

   were 
  obtained 
  from 
  the 
  same 
  locality, 
  and 
  rather 
  less 
  than 
  

   half 
  their 
  number 
  proved 
  to 
  lack 
  the 
  clitellum. 
  A 
  number 
  

   of 
  specimens 
  without 
  clitellum 
  have 
  also 
  been 
  found 
  in 
  various 
  

   other 
  localities. 
  

  

  