﻿INVEBTEBBATES. 
  355 
  

  

  of 
  the 
  body 
  is 
  across 
  the 
  lips, 
  where 
  the 
  section 
  is 
  strictly 
  pentagonal, 
  

   while 
  across 
  the 
  basals 
  it 
  is 
  obscurely 
  triangular. 
  Average 
  length 
  

   and 
  width, 
  as 
  taken 
  from 
  eleven 
  specimens, 
  as 
  eight 
  to 
  five, 
  actual 
  

   length 
  from 
  three 
  to 
  six-tenths 
  of 
  an 
  inch. 
  The 
  surface 
  of 
  the 
  test 
  

   is 
  perfectly 
  smooth, 
  without 
  ornamentation. 
  

  

  Basals 
  long, 
  in 
  form 
  of 
  an 
  elongate 
  cup 
  ; 
  column-like, 
  extended 
  at 
  

   the 
  lower 
  end; 
  upper 
  face 
  somewhat 
  excavated 
  for 
  the 
  reception 
  of 
  

   the 
  radials, 
  with 
  an 
  obtuse 
  angle 
  beneath 
  their 
  juncture. 
  

  

  Eadials 
  moderately 
  increasing 
  in 
  width 
  to 
  the 
  sinus. 
  The 
  length 
  

   of 
  the 
  radial 
  body 
  equal 
  to 
  or 
  surpassing 
  its 
  greatest 
  length, 
  

   and 
  equal 
  to 
  the 
  length 
  of 
  the 
  basals. 
  The 
  limbs 
  occcupy 
  

   less 
  than 
  one-third 
  the 
  entire 
  length 
  of 
  the 
  plate, 
  they 
  are 
  

   slightly 
  bent 
  inward, 
  those 
  of 
  two 
  contiguous 
  radials 
  forming 
  a 
  tri- 
  

   angle, 
  of 
  which 
  the 
  horizontal 
  side 
  (between 
  the 
  lips 
  of 
  the 
  adjoining 
  

   radials), 
  is 
  but 
  little 
  longer 
  than 
  the 
  two 
  lateral 
  sides. 
  At 
  the 
  anal 
  

   interadius. 
  the 
  upper 
  angle 
  is 
  truncated 
  by 
  the 
  anal 
  aperture, 
  and 
  

   the 
  outer 
  side 
  of 
  the 
  pyramid 
  is 
  more 
  sloping. 
  Sinus 
  short, 
  and 
  

   remarkably 
  deep. 
  

  

  The 
  oral 
  plates 
  are 
  small, 
  and 
  are 
  only 
  partly 
  exposed 
  to 
  view, 
  

   one 
  half 
  or 
  more 
  of 
  each 
  one 
  being 
  hidden 
  beneath 
  the 
  radials. 
  The 
  

   exposed 
  part, 
  which 
  consists 
  of 
  barely 
  more 
  than 
  what 
  might 
  be 
  

   called 
  the 
  lips 
  of 
  the 
  mouth, 
  is 
  slightly 
  projecting 
  along 
  the 
  margin 
  ; 
  

   it 
  is 
  in 
  form 
  rhomboidal, 
  but 
  the 
  angle 
  toward 
  the 
  radials 
  is 
  cov- 
  

   ered 
  by 
  the 
  tips 
  of 
  the 
  overlapping 
  limbs. 
  The 
  concealed 
  portions 
  

   are 
  at 
  the 
  four 
  lateral 
  interradii 
  placed 
  beneath 
  the 
  large 
  pyramids 
  

   which 
  have 
  been 
  described 
  ; 
  they 
  are 
  longer 
  than 
  wide, 
  and 
  their 
  

   distal 
  end 
  is 
  somewhat 
  extended 
  outward 
  and 
  downward. 
  The 
  me- 
  

   dian 
  portion 
  of 
  the 
  plate 
  is 
  provided 
  longitudinally 
  with 
  a 
  canal, 
  

   which 
  from 
  its 
  position 
  may 
  have 
  connected 
  the 
  hydropires 
  with 
  

   the 
  outer 
  vascular 
  ring. 
  The 
  description 
  of 
  the 
  oral 
  plates 
  is 
  made 
  

   principally 
  from 
  a 
  specimen, 
  in 
  which 
  the 
  greatest 
  part 
  of 
  the 
  ra- 
  

   dial 
  limbs 
  had 
  weathered 
  away, 
  thereby 
  exposing 
  the 
  parts 
  below. 
  

   As 
  seen 
  in 
  this 
  specimen, 
  the 
  lateral 
  sides 
  of 
  the 
  concealed 
  oral 
  

   plates 
  give 
  off 
  the 
  two 
  inner 
  hydrospires 
  for 
  each 
  group, 
  the 
  first 
  of 
  

   which, 
  at 
  several 
  places, 
  is 
  preserved 
  to 
  its 
  full 
  length 
  ; 
  the 
  second, 
  

   however, 
  is 
  recognized 
  only 
  by 
  a 
  stump, 
  and 
  there 
  is 
  a 
  notch 
  for 
  

   the 
  intermediate 
  slit. 
  The 
  oral 
  plate 
  of 
  the 
  anal 
  interradius 
  is 
  con- 
  

   structed 
  near 
  the 
  mouth 
  somewhat 
  different 
  from 
  the 
  orals 
  of 
  the 
  

   four 
  regular 
  sides 
  ; 
  the 
  parts 
  which 
  there 
  are 
  covered 
  by 
  the 
  limbs, 
  and 
  

   form 
  the 
  oral 
  ridges, 
  take 
  here 
  a 
  more 
  inward 
  direction, 
  and 
  com- 
  

   pose 
  the 
  sides 
  and 
  inner 
  floor 
  of 
  a 
  little 
  cavity, 
  which 
  forms 
  the 
  

  

  