﻿NO, 
  1955. 
  FOSSIL 
  INSECTS 
  FROM 
  COLORADO— 
  COCKERELL. 
  345 
  

  

  Wing 
  measurements 
  in 
  microns: 
  

  

  Depth 
  of 
  stigma, 
  about 
  368 
  

  

  Length 
  of 
  marginal 
  cell 
  2, 
  320 
  

  

  Width 
  (depth) 
  of 
  marginal 
  cell 
  528 
  

  

  Marginal 
  cell 
  on 
  first 
  submarginal 
  352 
  

  

  Marginal 
  cell 
  on 
  second 
  submarginal 
  880 
  

  

  Marginal 
  cell 
  from 
  second 
  (morphologically 
  third) 
  transversocubital 
  nervure 
  to 
  

  

  apex 
  1, 
  312 
  

  

  Basal 
  nervm-e 
  on 
  fii'st 
  submarginal 
  cell 
  400 
  

  

  Basal 
  nervure 
  on 
  first 
  discoidal 
  cell 
  (not 
  allowing 
  for 
  curvature) 
  1, 
  280 
  

  

  Length 
  (diagonal) 
  of 
  first 
  submarginal 
  cell 
  1, 
  408 
  

  

  Length 
  of 
  second 
  submarginal 
  cell 
  1, 
  728 
  

  

  Second 
  submarginal 
  cell 
  on 
  first 
  discoidal 
  480 
  

  

  Second 
  submarginal 
  cell 
  on 
  third 
  discoidal 
  1, 
  120 
  

  

  Second 
  submarginal 
  cell 
  from 
  insertion 
  of 
  second 
  recurrent 
  nerviu-e 
  to 
  apical 
  

  

  appendicular 
  nervure 
  112 
  

  

  Second 
  discoidal 
  cell 
  on 
  third 
  : 
  592 
  

  

  Apical 
  side 
  of 
  second 
  discoidal 
  cell 
  below 
  third 
  discoidal 
  352 
  

  

  Hind 
  wing: 
  

  

  Upper 
  end 
  of 
  transversomedial 
  nervure 
  to 
  basal 
  corner 
  of 
  discoidal 
  cell 
  (352 
  in 
  

  

  L. 
  antiquorum) 
  880 
  

  

  Discoidal 
  cell 
  on 
  median 
  (not 
  allowing 
  for 
  curvature) 
  (640 
  in 
  L. 
  antiquorum). 
  . 
  1, 
  216 
  

  

  Fig. 
  2.— 
  Pygidial 
  

  

  PLATE 
  OF 
  LlBELLU- 
  

   LAPIS 
  WILMATT^. 
  

  

  -Second 
  submarginal 
  cell 
  of 
  Libellulapis 
  

   wilmatt.e. 
  

  

  The 
  lower 
  side 
  of 
  the 
  first 
  submarginal 
  cell 
  is 
  faintly 
  arched 
  down- 
  

   wards, 
  but 
  almost 
  straight. 
  

  

  This 
  seems 
  certainly 
  to 
  belong 
  to 
  LibeUulajns, 
  which 
  was 
  based 
  * 
  

   on 
  a 
  species 
  (L. 
  antiquorum 
  Cockerell) 
  collected 
  by 
  Scudder 
  in 
  the 
  

   Florissant 
  shales. 
  A 
  reconsideration 
  of 
  the 
  genus 
  leads 
  me 
  to 
  place 
  

   in 
  the 
  Panurgidae, 
  where, 
  by 
  reason 
  of 
  certain 
  featm-es 
  of 
  the 
  

   venation, 
  it 
  appears 
  to 
  stand 
  rather 
  near 
  to 
  Panurgus. 
  The 
  broad 
  

   head, 
  with 
  prominent 
  eyes, 
  is 
  also 
  suggestive 
  of 
  certain 
  forms 
  of 
  

   Panurgus. 
  The 
  pygidial 
  plate 
  is 
  rather 
  approached 
  by 
  that 
  of 
  

   Dasijpoda. 
  

  

  In 
  Libellulapis 
  (both 
  species) 
  the 
  side 
  of 
  the 
  stigma 
  on 
  the 
  marginal 
  

   cell 
  is 
  practically 
  straight; 
  in 
  Pelandrena 
  (which 
  has 
  a 
  proportionally 
  

  

  Bull. 
  Mus. 
  Comp. 
  Zool., 
  vol. 
  50, 
  No. 
  2, 
  1906, 
  p. 
  42. 
  

  

  