﻿OF 
  THE 
  UNITED 
  STATES. 
  407 
  

  

  or 
  sculpture 
  If, 
  consequently, 
  any 
  doubt 
  still 
  remains 
  in 
  the 
  determination 
  of 
  the 
  species, 
  

   it 
  results 
  from 
  the 
  inherent 
  difficulty 
  of 
  the 
  subject, 
  which 
  would 
  not 
  be 
  removed 
  by 
  a 
  

   greater 
  amount 
  of 
  detail. 
  

  

  Proceeding 
  now 
  to 
  the 
  principles 
  employed 
  in 
  the 
  classification 
  of 
  the 
  species, 
  we 
  must 
  

   first 
  inquire 
  into 
  the 
  natural 
  limits 
  of 
  the 
  group. 
  

  

  The 
  family 
  of 
  Elateridae 
  has 
  always 
  been 
  considered 
  as 
  closely 
  allied 
  to 
  the 
  Buprestida?, 
  

   in 
  which 
  also 
  the 
  prosternum 
  is 
  prolonged 
  posteriorly 
  and 
  received 
  into 
  the 
  excavated 
  me- 
  

   sosternum; 
  nevertheless, 
  on 
  comparison, 
  great 
  differences 
  are 
  found: 
  in 
  the 
  Buprestida^ 
  

   although 
  the 
  anterior 
  coxa? 
  are 
  small 
  and 
  globular, 
  the 
  acetabula 
  in 
  which 
  they 
  are 
  re- 
  

   ceived 
  are 
  composed 
  partly 
  of 
  the 
  epimera 
  of 
  the 
  mesothorax, 
  while 
  in 
  Elaterida? 
  the 
  ace- 
  

   tabula, 
  although 
  open 
  posteriorly, 
  are 
  confined 
  to 
  the 
  prosternum; 
  the 
  prothorax 
  thus 
  ac- 
  

   quires 
  a 
  greater 
  degree 
  of 
  mobility 
  than 
  is 
  seen 
  in 
  the 
  Buprestidse: 
  the 
  same 
  structure 
  is 
  

   seen 
  in 
  the 
  Throscites 
  that 
  has 
  been 
  just 
  noticed 
  in 
  the 
  Buprestida?. 
  Other 
  differences 
  

   are 
  seen 
  in 
  the 
  structure 
  of 
  the 
  abdomen: 
  the 
  suture 
  between 
  the 
  first 
  and 
  second 
  se^- 
  

   ments 
  is 
  more 
  or 
  less 
  obliterated 
  in 
  Buprestida?, 
  while 
  in 
  all 
  Elaterida) 
  it 
  is 
  as 
  distinct 
  as 
  

   the 
  other 
  sutures. 
  

  

  From 
  the 
  other 
  groups 
  of 
  scrricorn 
  pentamerous 
  Coleoptera, 
  the 
  Elaterida? 
  are 
  distin- 
  

   guished 
  by 
  the 
  small 
  globular 
  anterior 
  coxa? 
  and 
  the 
  prolonged 
  prosternum. 
  The 
  combi- 
  

   nation 
  then 
  of 
  the 
  four 
  following 
  characters 
  will 
  define 
  the 
  family, 
  as 
  understood 
  by 
  me: 
  

  

  Coxre 
  anticre 
  parvaj 
  rotundata?, 
  non 
  contigure 
  in 
  prosterno 
  sitre, 
  acctabulis 
  postice 
  hientibus 
  ; 
  pros- 
  

   ternum 
  pone 
  coxas 
  productum, 
  pracipue 
  mucronatum, 
  in 
  mesosterno 
  excavato 
  recepturn 
  ; 
  abdomen 
  

   suturis 
  ventralibus 
  omnibus 
  distinctis; 
  tarsi 
  5-articulati. 
  

  

  This 
  definition 
  includes 
  the 
  so-called 
  families 
  of 
  Eucnemides 
  and 
  Cebrionides, 
  which 
  

   differ 
  by 
  unimportant 
  characters, 
  from 
  the 
  genuine 
  Elaterides. 
  The 
  value 
  of 
  these 
  cha- 
  

   racters 
  will 
  be 
  presently 
  discussed. 
  Accompanying 
  the 
  four 
  essentia] 
  characters 
  above 
  

   given, 
  there 
  are 
  others 
  of 
  great 
  constancy, 
  such 
  as: 
  

  

  The 
  antenna? 
  are 
  serrate, 
  flabellate, 
  or 
  pectinate, 
  rarely 
  subfiliform, 
  never 
  clavate, 
  or 
  

   capitulate; 
  in 
  the 
  males 
  only 
  of 
  certain 
  Eucnemides 
  are 
  the 
  terminal 
  joints 
  enlarged, 
  but 
  

   they 
  always 
  preserve 
  their 
  serricorn 
  type. 
  The 
  eyes 
  are 
  round, 
  (in 
  Perothops 
  alone 
  are 
  they 
  

   slightly 
  oval,) 
  and 
  never 
  emarginate; 
  the 
  antenna? 
  are 
  inserted 
  in 
  fovea?, 
  the 
  upper 
  mar- 
  

   gins 
  of 
  which 
  are 
  more 
  or 
  less 
  defined, 
  usually 
  under 
  the 
  side 
  of 
  the 
  front, 
  immediately 
  in 
  

   front 
  of 
  the 
  eyes; 
  in 
  Eucnemides 
  the 
  fovea 
  becomes 
  a 
  sinus, 
  which 
  contracts 
  the 
  front 
  at 
  

   the 
  middle, 
  and 
  the 
  antenna? 
  approach 
  each 
  other, 
  thus 
  becoming 
  farther 
  removed 
  from 
  

   the 
  eyes. 
  The 
  mandibles 
  are 
  usually 
  small 
  and 
  retracted; 
  in 
  Cebrionides 
  they 
  arc 
  longer 
  

   and 
  prominent; 
  the 
  labrum 
  is 
  distinct 
  in 
  the 
  true 
  Elaterides, 
  indistinct 
  in 
  the 
  other 
  groups; 
  

   the 
  prosternum 
  is 
  lobed 
  in 
  nearly 
  all 
  of 
  the 
  true 
  Elaterides; 
  not 
  lobed 
  in 
  Campylus, 
  Oes- 
  

   todes, 
  Eucnemides, 
  and 
  Cebrionides; 
  the 
  head 
  is 
  deflexed, 
  and 
  the 
  mouth 
  entirely 
  covered 
  

   in 
  the 
  Eucnemides 
  (except 
  Melasis 
  and 
  Tharops;) 
  it 
  is 
  applied 
  against 
  the 
  lobe 
  of 
  the 
  

   prosternum, 
  and 
  consequently 
  moderately 
  deflexed 
  in 
  most 
  Elaterides; 
  not 
  deflexed, 
  but 
  

   free 
  in 
  Campylus, 
  Oestodes, 
  and 
  in 
  the 
  Cebrionides; 
  the 
  posterior 
  thighs 
  are 
  retractile 
  

   under 
  the 
  dilated 
  plates 
  of 
  the 
  coxa>, 
  except 
  in 
  Cerophytum, 
  where 
  the 
  coxal 
  plates 
  are 
  

   obsolete; 
  the 
  plate 
  is 
  slightly 
  emarginate, 
  and 
  usually 
  toothed 
  at 
  the 
  internal 
  angle, 
  thus 
  

   vol. 
  x.— 
  G9. 
  

  

  