﻿MELOLONTIIID^E 
  OF 
  THE 
  UNITED 
  STATES. 
  233 
  

  

  scales. 
  Pectus 
  densely 
  clothed 
  with 
  long 
  yellowish 
  hair. 
  Femora 
  and 
  inner 
  margin 
  

   of 
  the 
  posterior 
  tibiae 
  fringed 
  with 
  long 
  hair. 
  

  

  [3. 
  RHIZOTROGI. 
  

  

  These 
  are 
  distinguished 
  among 
  the 
  other 
  Melolonthida? 
  with 
  transverse 
  not 
  promi- 
  

   nent 
  anterior 
  coxa?, 
  by 
  the 
  deeply 
  emarginate 
  labrum, 
  the 
  anteriorly 
  margined 
  thorax 
  

   without 
  apical 
  membrane, 
  the 
  narrow 
  parapleural, 
  and 
  the 
  connate 
  ventral 
  segments. 
  

   Specimens, 
  and 
  perhaps 
  even 
  species 
  occur 
  in 
  which 
  this 
  last 
  character 
  is 
  not 
  very 
  

   obvious. 
  

  

  Additional 
  characters, 
  not 
  previously 
  noticed 
  are 
  : 
  the 
  5th 
  ventral 
  segment 
  is 
  joined 
  

   with 
  the 
  propygidium 
  by 
  an 
  angulated 
  suture, 
  which 
  is 
  sometimes 
  partly 
  obliterated, 
  

   the 
  stigma 
  is 
  placed 
  upon 
  the 
  suture 
  at 
  the 
  angle, 
  and 
  nearer 
  the 
  posterior 
  than 
  the 
  

   anterior 
  margin. 
  

  

  The 
  last 
  joint 
  of 
  the 
  maxillary 
  palpi 
  is 
  frequently 
  impressed 
  and 
  sometimes 
  deeply 
  

   excavated, 
  the 
  ungues 
  and 
  mandibles 
  seem 
  to 
  vary 
  in 
  form 
  within 
  the 
  same 
  genus. 
  

   In 
  the 
  native 
  genera 
  the 
  posterior 
  coxa? 
  are 
  entirely 
  corneous, 
  without 
  any 
  posterior 
  

   membranous 
  margin 
  : 
  the 
  posterior 
  external 
  angle 
  is 
  sometimes 
  produced 
  ; 
  the 
  antenna? 
  

   are 
  9 
  or 
  10-jointed, 
  with 
  the 
  club 
  three-jointed. 
  

   Our 
  genera 
  may 
  be 
  thus 
  arranged 
  : 
  

  

  Unguiculi 
  haud 
  serrati, 
  prope 
  medium 
  dentati 
  ; 
  

   Ligula 
  profunde 
  emarginata 
  ; 
  

  

  Antennae 
  lOarticulatse 
  ..... 
  Eugastra 
  Lee. 
  

  

  Antennae 
  9-articulatae 
  • 
  Endrosa 
  Lee. 
  

  

  Ligula 
  fere 
  truneata 
  ; 
  

  

  Labrum 
  bilobum 
  Lachnosterna 
  Hope. 
  

  

  Labrum 
  concavum, 
  haud 
  bilobum 
  ..... 
  . 
  Gynnis 
  Lee. 
  

  

  Unguiculi 
  plus 
  minusve 
  serrati, 
  nonnunquam 
  ad 
  medium 
  dentati 
  ; 
  ligula 
  fere 
  truneata 
  Listrochelus 
  Blanch. 
  

  

  Eugastra 
  Lee. 
  

  

  Corpus 
  crassum, 
  convexum, 
  sexus 
  utriusque 
  apterum, 
  supra 
  et 
  subtus 
  glabrum. 
  Labrum 
  bilobum 
  ; 
  man- 
  

   dibulee 
  proniinulae, 
  maxillae 
  validae 
  ad 
  apicem 
  dentatae. 
  Ligula 
  parum 
  concava, 
  antice 
  profunde 
  subquad- 
  

   ratini 
  emarginata. 
  Palpi 
  maxillares 
  articulo 
  ultimo 
  elongato, 
  levissime 
  obovali, 
  labiales 
  articulo 
  ultimo 
  

   ovali. 
  Antennae 
  lO-artieulatas, 
  articulis 
  3 
  — 
  6 
  subrcqualibus, 
  7mo 
  breviore, 
  haud 
  latiore; 
  clava 
  sexus 
  utrius- 
  

   que 
  parva 
  triphylla. 
  Tibiae 
  posteriores 
  coronatae, 
  tarsi 
  tibiis 
  paulo 
  longiores, 
  setosi, 
  postici 
  articulo 
  lmo 
  vix 
  

   breviore 
  ; 
  unguiculis 
  dente 
  acuto 
  prope 
  basin 
  armatis 
  ; 
  calcaribus 
  posticis 
  sexus 
  utriusque 
  liberis. 
  Abdomen 
  

   segmento 
  ventrali 
  ultimo 
  feminae 
  prominulo, 
  maris 
  brevi 
  ; 
  penultiuio 
  maris 
  aequali, 
  feminae 
  transversim 
  

   impresso. 
  

  

  This 
  genus 
  represents 
  on 
  this 
  continent 
  the 
  apterous 
  Rhizotrogi 
  of 
  the 
  group 
  Geo- 
  

   trogus, 
  but 
  differs 
  from 
  that 
  genus 
  by 
  many 
  characters. 
  The 
  deep 
  emargination 
  of 
  

   the 
  ligula 
  is 
  bisinuous 
  but 
  almost 
  square 
  at 
  base, 
  and 
  will 
  readily 
  distinguish 
  this 
  

  

  from 
  all 
  the 
  other 
  genera 
  of 
  the 
  tribe. 
  

  

  60 
  

  

  