﻿EPHEMERINA. 
  335 
  

  

  regard 
  as 
  the 
  epimerum 
  appears 
  to 
  be 
  the 
  sclerite 
  e 
  m" 
  (Fig. 
  2), 
  which 
  

   in 
  the 
  sketch 
  is 
  situated 
  directly 
  under 
  the 
  metanotum. 
  

  

  Sternum. 
  

  

  Prosternum. 
  This 
  is 
  a 
  small 
  triangular 
  area 
  situated 
  between 
  the 
  

   insertion 
  of 
  the 
  legs. 
  

  

  Mesosternum. 
  This 
  is 
  a 
  very 
  large 
  region 
  divided 
  into 
  a 
  prsesternitc 
  

   and 
  sternite. 
  The 
  former 
  is 
  narrow, 
  as 
  long 
  as 
  broad, 
  the 
  surface 
  con- 
  

   vex. 
  The 
  sternite 
  is 
  divided 
  iuto 
  two 
  large, 
  loug, 
  oval 
  portions 
  extend- 
  

   ing 
  far 
  back 
  of 
  the 
  insertion 
  of 
  the 
  legs. 
  

  

  Metasternum, 
  This 
  sclerite 
  is 
  very 
  short, 
  small 
  and 
  rudimentary. 
  

  

  THE 
  ABDOMEN. 
  

  

  There 
  are 
  ten 
  abdominal 
  segments. 
  The 
  first 
  tergite 
  is 
  wanting, 
  the 
  

   tenth 
  is 
  a 
  supra-anal 
  plate. 
  There 
  are 
  nine 
  urosternites 
  j 
  the 
  basal 
  is 
  

   large 
  and 
  long, 
  with 
  a 
  pair 
  of 
  spiracles. 
  The 
  11th 
  uromere 
  may 
  be 
  repre- 
  

   sented 
  by 
  the 
  median 
  articulated 
  appendage? 
  situated 
  between 
  the 
  two 
  

   very 
  long 
  multi-articulated 
  cercopoda. 
  The 
  10th 
  urite 
  is 
  represented 
  

   by 
  two 
  long, 
  oval, 
  parallel 
  plates. 
  

  

  A 
  remarkable 
  feature 
  of 
  the 
  male 
  Ephemerina 
  is 
  the 
  two 
  pairs 
  of 
  

   jointed 
  appendages 
  rising 
  from 
  beneath 
  the 
  cercopoda. 
  These 
  may 
  

   be 
  regarded 
  as 
  homologues 
  of 
  two 
  pairs 
  of 
  the 
  rhabdites 
  composing 
  the 
  

   ovipositor 
  of 
  the 
  female 
  of 
  other 
  insects. 
  The 
  lower 
  pair 
  (Fig. 
  1 
  rh) 
  

   is 
  3-jointed 
  (perhaps 
  4-jointed), 
  while 
  the 
  upper 
  pair 
  (rh') 
  is 
  2-jointed. 
  

   We 
  know 
  of 
  no 
  other 
  insects 
  which 
  have 
  two 
  pairs 
  of 
  jointed 
  claspers. 
  

   These 
  singular 
  organs 
  may 
  be 
  called 
  rhahdopoda. 
  They 
  appear 
  to 
  be 
  

   homologues 
  of 
  the 
  abdominal 
  feet 
  of 
  Myriapods, 
  the 
  abdominal 
  legs 
  of 
  

   Tenthredinid 
  and 
  Lepidopterous 
  larvse, 
  and 
  the 
  spinnerets 
  of 
  spiders. 
  

  

  The 
  adult 
  Ephemerina, 
  then, 
  in 
  the 
  lack 
  of 
  mouth-parts, 
  in 
  the 
  con- 
  

   centrated 
  thorax, 
  and 
  the 
  possession 
  of 
  two 
  pairs 
  of 
  abdominal 
  jointed 
  

   appendages, 
  differ 
  remarkably 
  from 
  the 
  Odonata 
  and 
  other 
  Phyloptera, 
  

   so 
  that 
  we 
  are 
  nearly 
  justified 
  in 
  regarding 
  the 
  group 
  as 
  entitled 
  to 
  rank 
  

   as 
  a 
  suborder. 
  

  

  Order 
  NEUEOPTERA 
  (as 
  restricted 
  by 
  Ericlison). 
  

  

  Suborder 
  1. 
  Planipennia. 
  

  

  Family 
  SIALID^. 
  

  

  THE 
  HEAD. 
  

  

  Cory 
  dolus 
  cornutus. 
  (PI. 
  LIT, 
  figs. 
  1-3.) 
  Head 
  very 
  broad 
  and 
  flat 
  j 
  ver- 
  

   tex 
  remarkably 
  large, 
  broad, 
  long, 
  and 
  flat, 
  forming 
  the 
  bulk 
  of 
  the 
  epi- 
  

   cranium. 
  Ocelli 
  three, 
  large, 
  but 
  the 
  ocellar 
  area 
  is 
  small, 
  with 
  no 
  suture 
  ; 
  

   the 
  ante-antennal 
  (orbital) 
  fossae 
  large 
  and 
  conspicuous, 
  transversely 
  

   oval 
  above, 
  beneath 
  curvilinear. 
  No 
  suture 
  between 
  the 
  clypeus 
  and 
  

  

  