﻿INVERTEBRATES. 
  347 
  

  

  Messrs. 
  Etheridge 
  and 
  Carpenter 
  have 
  lately 
  published 
  through 
  

   the 
  Ann. 
  and 
  Mag. 
  Nat. 
  Hist., 
  April, 
  1882, 
  an 
  interesting 
  paper, 
  

   "On 
  certain 
  points 
  in 
  the 
  Morphology 
  of 
  the 
  Blastoidea, 
  with 
  descrip- 
  

   tions 
  of 
  some 
  new 
  Genera 
  and 
  Species," 
  in 
  which 
  they 
  explain 
  the 
  

   terms 
  which 
  they 
  propose 
  to 
  use 
  in 
  their 
  writings. 
  Their 
  terms 
  are 
  

   in 
  conformity 
  with 
  those 
  now 
  in 
  use 
  for 
  the 
  Crinoids 
  and 
  other 
  

   Echinoderms, 
  and 
  it 
  would 
  be 
  of 
  great 
  advantage 
  to 
  science 
  if 
  they 
  

   were 
  universally 
  adopted 
  by 
  future 
  writers 
  upon 
  Blastoids. 
  In 
  order 
  

   to 
  give 
  this 
  terminology 
  a 
  wider 
  circulation, 
  and 
  for 
  the 
  better 
  com- 
  

   prehension 
  of 
  the 
  succeeding 
  descriptions, 
  I 
  give 
  here 
  an 
  abstract 
  

   of 
  their 
  principal 
  terms. 
  

  

  The 
  "calyx,'" 
  according 
  to 
  Etheridge 
  and 
  Carpenter, 
  is 
  composed 
  

   of 
  the 
  "basals" 
  the 
  "radials" 
  or 
  forked 
  pieces, 
  and 
  the 
  "orals" 
  or 
  

   deltoid 
  pieces. 
  The 
  suture 
  between 
  basals 
  and 
  radials 
  is 
  the 
  "basi- 
  

   radial 
  suture 
  ;" 
  the 
  more 
  or 
  less 
  strongly 
  marked 
  ridge 
  at 
  the 
  median 
  

   line 
  of 
  each 
  oral 
  is 
  the 
  "oral 
  ridge." 
  In 
  the 
  forked-shaped 
  radials, 
  

   the 
  handle 
  of 
  the 
  fork 
  is 
  the 
  "body" 
  of 
  the 
  radial, 
  the 
  two 
  prongs 
  

   are 
  the 
  "limbs;" 
  between 
  the 
  limbs 
  is 
  the 
  "radial 
  sinus," 
  which 
  is 
  

   occupied 
  by 
  the 
  "ambulacrum." 
  Of 
  the 
  ambulacral 
  structures, 
  which 
  

   together 
  fill 
  up 
  the 
  radial 
  sinus 
  to 
  a 
  greater 
  or 
  less 
  extent, 
  the 
  most 
  

   important 
  is 
  the 
  "lancet-piece," 
  which 
  is 
  excavated 
  lengthwise 
  by 
  the 
  

   "food-groove 
  or 
  ambulacrum 
  proper." 
  Upon 
  or 
  against 
  it 
  rest 
  the 
  

   "side-plates," 
  pore-pieces 
  of 
  Eoemer; 
  they 
  are 
  marked 
  by 
  minute 
  

   pits, 
  the 
  "pinnule 
  pits 
  or 
  sockets," 
  which 
  must 
  not 
  be 
  confounded 
  

   with 
  the 
  marginal 
  pores 
  or 
  "hydrospire-pores." 
  The 
  supplementary 
  

   pore-pieces 
  of 
  Roemer 
  are 
  the 
  "outer 
  side 
  plates." 
  Beneath 
  the 
  am- 
  

   bulacral 
  fields 
  are 
  the 
  "interradial 
  systems 
  of 
  lamellar 
  tubes 
  or 
  hydro- 
  

   spires." 
  The 
  openings 
  of 
  these 
  tubes, 
  if 
  directly 
  on 
  the 
  ventral 
  

   surface 
  of 
  the 
  calyx 
  as 
  in 
  Codaster, 
  are 
  called 
  the 
  "hydrospire-slits 
  ;" 
  

   if 
  they 
  are 
  concentrated 
  beneath 
  the 
  ambulacra 
  as 
  in 
  Orophocrinus 
  * 
  

   the 
  gap 
  between 
  the 
  edge 
  of 
  the 
  lancet-plate 
  and 
  the 
  sides 
  of 
  the 
  

   radial 
  sinus 
  is 
  the 
  "hydrospire 
  cleft." 
  This 
  leads 
  downward 
  into 
  the 
  

   "hydrospire 
  canal." 
  The 
  canals 
  open 
  externally 
  by 
  the 
  "spiracles," 
  

   formerly 
  called 
  ovarian 
  openings. 
  The 
  spiracle 
  or 
  spiracles 
  of 
  the 
  

   anal 
  interradius 
  may 
  be 
  confluent 
  with 
  the 
  anal 
  opening 
  to 
  form 
  

   the 
  "anal 
  spiracle." 
  The 
  plates 
  covering 
  the 
  mouth 
  and 
  peristome, 
  and 
  

   which 
  are 
  sometimes 
  continued 
  down 
  the 
  ambulacra 
  covering 
  the 
  food 
  

   grooves," 
  are 
  the 
  "summit 
  plates 
  or 
  the 
  vault." 
  

  

  *MEEKand 
  Worthen 
  in 
  defining, 
  in 
  1809, 
  (Geol. 
  Rep. 
  111., 
  Vol. 
  V, 
  p. 
  404) 
  tho 
  genus 
  Oodon 
  

   ites, 
  were 
  evidently 
  not 
  aware 
  that 
  Von 
  Beebach 
  had 
  proposed, 
  in 
  1801, 
  (Nachr. 
  K. 
  

   Geselloeh. 
  zu 
  U-oettingen, 
  p. 
  HOj 
  for 
  Pentremit 
  s 
  stelliformis 
  Owen 
  and 
  Shum. 
  the 
  genus 
  

   Orophocrinus. 
  The 
  latter 
  has 
  since 
  been 
  adopted 
  by 
  Ludwig, 
  Zittel 
  and 
  by 
  Etheridge 
  and 
  

   Carpenter. 
  

  

  