﻿552 
  PROCEEDINGS 
  OF 
  THE 
  NATIONAL 
  MUSEUM 
  vol. 
  io3 
  

  

  Family 
  Periscelidae 
  

  

  Auxiliary 
  vein 
  rudimentary, 
  ending 
  free 
  (not 
  apically 
  fused 
  with 
  

   costa 
  or 
  first 
  vein); 
  no 
  costal 
  breaks; 
  anal 
  cell 
  present; 
  fin^t 
  vein 
  

   ending 
  well 
  distal 
  to 
  basal 
  third 
  of 
  wing; 
  costa 
  ending 
  at 
  apex 
  of 
  third 
  

   vein 
  ; 
  second 
  antennal 
  segment 
  with 
  one 
  or 
  more 
  dorsal 
  apical 
  bristles, 
  

   rather 
  long 
  third 
  segment 
  arising 
  from 
  its 
  ventral 
  surface; 
  arista 
  

   plumose; 
  face 
  strongly 
  receding 
  below, 
  extending 
  laterally 
  below 
  the 
  

   buccae, 
  narrowed 
  below 
  the 
  antennae 
  by 
  the 
  anterior 
  extension 
  of 
  the 
  

   eyes 
  (the 
  longest 
  diameter 
  of 
  the 
  latter 
  being 
  oblique) 
  ; 
  bucca 
  extending 
  

   upward 
  anteriorly, 
  bearing 
  a 
  row 
  of 
  bristles, 
  of 
  which 
  the 
  anterior 
  is 
  

   placed 
  well 
  above 
  the 
  oral 
  margin; 
  hairs 
  on 
  lateral 
  portions 
  of 
  face; 
  

   one 
  reclinate 
  orbital 
  bristle; 
  no 
  preapicals 
  on 
  tibiae; 
  postverticals 
  

   divergent; 
  no 
  presutural 
  dorsocentral; 
  scutellum 
  with 
  four 
  marginal 
  

   bristles, 
  its 
  disc 
  bare. 
  

  

  Genus 
  Periscelis 
  Loew, 
  1858 
  

  

  I 
  have 
  suggested 
  elsewhere 
  that 
  Microperiscelis 
  Oldenberg 
  (type, 
  

   Notiphila 
  annulata 
  Fallen) 
  is 
  antedated 
  by 
  the 
  isogenotypic 
  Myodris 
  

   Lioy 
  and 
  that 
  the 
  genus 
  is 
  scarcely 
  valid. 
  The 
  properties 
  of 
  the 
  new 
  

   species 
  described 
  here 
  have 
  led 
  me 
  to 
  conclude 
  that 
  Sphyroperiscelis 
  

   Sturtevant 
  is 
  also 
  best 
  considered 
  a 
  synonym 
  of 
  Periscelis. 
  There 
  are 
  

   11 
  or 
  12 
  species 
  of 
  the 
  family 
  known 
  from 
  the 
  world, 
  and 
  five 
  genera 
  

   are 
  recognized 
  here, 
  even 
  though 
  Myodris 
  and 
  Sphyroperiscelis 
  are 
  not 
  

   accepted 
  (see 
  list, 
  p. 
  556). 
  For 
  convenience, 
  the 
  use 
  of 
  broad 
  

   generic 
  limits 
  is 
  desirable 
  here. 
  If 
  both 
  the 
  names 
  under 
  considera- 
  

   tion 
  are 
  retained 
  it 
  will 
  not 
  be 
  easy 
  to 
  fit 
  the 
  new 
  species 
  iuto 
  any 
  of 
  

   the 
  available 
  categories, 
  and 
  a 
  new 
  genus 
  will 
  be 
  indicated, 
  giving 
  8 
  

   genera 
  for 
  12 
  species. 
  

  

  Key 
  to 
  the 
  Nearctic 
  species 
  of 
  Periscelis 
  

  

  1. 
  Mesonotum 
  dull 
  gray, 
  with 
  a 
  brown 
  median 
  stripe; 
  posterior 
  cross 
  vein 
  

  

  strong 
  P. 
  annulata 
  (Fallen) 
  

  

  Mesonotum 
  rather 
  shining 
  black; 
  posterior 
  crossvein 
  faint 
  or 
  largely 
  absent. 
  .2 
  

  

  2. 
  Antennal 
  bases 
  about 
  as 
  far 
  from 
  each 
  other 
  as 
  each 
  is 
  from 
  eye; 
  posterior 
  

  

  crossvein 
  represented 
  by 
  stumps 
  at 
  each 
  end 
  P. 
  wheeleri 
  (Sturtevant) 
  

  

  Antennal 
  bases 
  much 
  nearer 
  each 
  other 
  than 
  to 
  eyes; 
  posterior 
  crossvein 
  

   complete 
  but 
  faint 
  P. 
  occidentalis, 
  new 
  species 
  

  

  Female 
  genitalia: 
  I 
  have 
  described 
  the 
  internal 
  reproductive 
  

   systems 
  of 
  Periscelis 
  annulata 
  and 
  P. 
  wheeleri 
  (Sturtevant, 
  1926, 
  p. 
  7). 
  

   These 
  species 
  are 
  much 
  alike, 
  and 
  are 
  very 
  different 
  from 
  any 
  other 
  

   known 
  forms, 
  especially 
  in 
  that 
  they 
  have 
  three 
  chitinized 
  sperma- 
  

   thecae 
  that 
  are 
  attached 
  directly 
  to 
  a 
  singly 
  common 
  duct. 
  They 
  are 
  

   also 
  unusual 
  in 
  that 
  the 
  eggs 
  are 
  blackish 
  brown 
  in 
  color. 
  

  

  