﻿INVEETEBEATES. 
  361 
  

  

  EljEACbinus 
  meloniformis, 
  Barris, 
  Nov. 
  sp. 
  

  

  Body 
  small, 
  ovoid, 
  height 
  nearly 
  one-half 
  more 
  than 
  the 
  width; 
  

   greatest 
  width 
  through 
  the 
  median 
  part, 
  or 
  a 
  little 
  above 
  ; 
  curvature 
  

   toward 
  the 
  two 
  poles 
  nearly 
  equal, 
  but 
  the 
  pole 
  itself 
  at 
  the 
  abac- 
  

   tinal 
  side 
  abruptly 
  depressed, 
  and 
  the 
  concavity 
  perfectly 
  filled 
  by 
  

   the 
  column. 
  Surface 
  of 
  the 
  ambulacra 
  raised 
  but 
  little 
  above 
  the 
  

   general 
  plane 
  of 
  the 
  body. 
  The 
  plates 
  along 
  the 
  sides 
  of 
  the 
  am- 
  

   bulacra 
  are 
  marked 
  with 
  obscure 
  transverse 
  grooves, 
  bordered 
  at 
  

   each 
  side 
  by 
  a 
  sharp 
  ridge, 
  which 
  forms 
  along 
  the 
  median 
  por- 
  

   tions 
  of 
  the 
  plate 
  a 
  deltoid-like 
  figure. 
  The 
  ridges 
  which 
  join 
  with 
  

   one 
  end 
  at 
  the 
  summit, 
  with 
  the 
  other 
  at 
  the 
  radial 
  lips, 
  form 
  to- 
  

   gether 
  around 
  the 
  body 
  a 
  well 
  marked 
  penta-petaloid 
  figure 
  in 
  which 
  

   the 
  ambulacra 
  are 
  placed 
  along 
  the 
  median 
  line 
  ; 
  and 
  as 
  the 
  ridges 
  

   in 
  this 
  species 
  happen 
  to 
  be 
  more 
  conspicuous 
  than 
  the 
  margins 
  of 
  

   the 
  ambulacra, 
  the 
  ridges 
  appear 
  as 
  the 
  boundaries 
  of 
  the 
  latter. 
  

   Cross-section 
  along 
  the 
  upper 
  half 
  of 
  the 
  body 
  obscurely 
  decagonal, 
  

   almost 
  circular, 
  decidedly 
  pentagonal 
  across 
  the 
  lips 
  of 
  the 
  radials. 
  

  

  Basals 
  small, 
  entirely 
  hidden 
  within 
  the 
  columnar 
  cavity. 
  

  

  Eadials 
  small, 
  body 
  part 
  longer 
  than 
  usual 
  in 
  this 
  genus, 
  their 
  

   lower 
  portions 
  resting 
  within 
  the 
  concavity, 
  whence 
  they 
  bend 
  

   abruptly 
  in 
  an 
  opposite 
  direction, 
  forming 
  a 
  sharp 
  edge 
  at 
  the 
  end 
  

   of 
  the 
  body. 
  Length 
  more 
  than 
  twice 
  the 
  width 
  at 
  the 
  basi-radial 
  

   suture, 
  which 
  is 
  about 
  equal 
  to 
  the 
  width 
  of 
  a 
  limb 
  at 
  its 
  upper 
  

   side. 
  Sinus 
  very 
  short 
  enclosing 
  but 
  little 
  more 
  than 
  the 
  lip, 
  which 
  

   is 
  strongly 
  protruding, 
  and 
  from 
  which 
  a 
  very 
  prominent 
  rounded 
  

   ridge 
  proceeds 
  to 
  the 
  lower 
  edge 
  of 
  the 
  plate. 
  The 
  upper 
  sides 
  of 
  

   the 
  limbs 
  are 
  convex, 
  with 
  a 
  re-entering 
  angle 
  above 
  the 
  lateral 
  

   sutures. 
  

  

  Oral 
  plates 
  large, 
  occupying 
  four-fifths 
  of 
  the 
  length 
  of 
  the 
  entire 
  

   body, 
  divided 
  by 
  two 
  raised 
  lines 
  into 
  three 
  parts, 
  the 
  inner 
  or 
  

   deltoid 
  part 
  provided 
  with 
  fine 
  granules, 
  the 
  outer 
  part 
  with 
  trans- 
  

   verse 
  grooves, 
  which 
  are 
  equal 
  to 
  the 
  number 
  of 
  side 
  plates 
  in 
  the 
  

   ambulacra. 
  The 
  anal 
  plate 
  which 
  divides 
  the 
  oral 
  piece 
  of 
  the 
  pos- 
  

   terior 
  interradius, 
  differs 
  in 
  form 
  but 
  little 
  from 
  the 
  deltoid-shaped 
  

   portions 
  of 
  the 
  other 
  four 
  interradial 
  sides 
  ; 
  it 
  is 
  however 
  a 
  little 
  

   wider, 
  and 
  at 
  the 
  upper 
  end 
  protruding 
  outward. 
  The 
  anal-aperture 
  

   is 
  large, 
  rhomboidal, 
  the 
  opening 
  in 
  an 
  upward 
  direction. 
  It 
  is 
  

   bordered 
  towards 
  the 
  peristome 
  by 
  two 
  summit 
  plates 
  which 
  rest 
  

   against 
  the 
  upper 
  ends 
  of 
  the 
  two 
  sections 
  of 
  the 
  oral 
  plate. 
  

  

  —24 
  

  

  