﻿WEIGHT 
  AND 
  ADAMS 
  MALTESE 
  ECHINODERMS. 
  475 
  

  

  plate 
  bulging 
  out 
  in 
  the 
  middle 
  and 
  being 
  depressed 
  at 
  the 
  suture 
  ; 
  

   each 
  plate 
  is 
  oblong, 
  and 
  has 
  its 
  mammillary 
  eminence 
  nearer 
  the 
  

   poriferous 
  zones 
  than 
  the 
  median 
  suture 
  ; 
  a 
  circle 
  of 
  small 
  tubercles 
  

   surrounds 
  the 
  areola, 
  and 
  forms 
  a 
  moniliform 
  boundary 
  ; 
  the 
  rest 
  of 
  

   the 
  surface 
  of 
  the 
  plate 
  is 
  thickly 
  studded 
  with 
  regular 
  rows 
  of 
  very 
  

   fine 
  prominent 
  granules 
  ; 
  median 
  suture 
  much 
  depressed, 
  forming 
  a 
  

   marked 
  concavity 
  entirely 
  filled 
  with 
  regular 
  rows 
  of 
  fine 
  granules. 
  

   The 
  summit 
  of 
  the 
  boss 
  is 
  smooth, 
  and 
  without 
  any 
  trace 
  of 
  crenu- 
  

   lations 
  ; 
  the 
  tubercle 
  is 
  large 
  with 
  a 
  wide 
  hole. 
  

  

  The 
  only 
  fragment 
  found 
  is 
  the 
  one 
  under 
  description. 
  It 
  consists 
  

   of 
  a 
  portion 
  only 
  of 
  two 
  columns 
  of 
  interambulacral 
  plates, 
  four 
  in 
  

   each 
  row, 
  with 
  the 
  half 
  of 
  the 
  adjoining 
  ambulacral 
  area 
  and 
  pori- 
  

   ferous 
  zone 
  in 
  situ. 
  

  

  I 
  am 
  not 
  acquainted 
  with 
  any 
  allied 
  form 
  of 
  Cidaris. 
  The 
  pro- 
  

   minence 
  of 
  the 
  columns 
  of 
  interambulacral 
  plates, 
  and 
  the 
  regularity 
  

   of 
  the 
  tuberculation 
  on 
  the 
  other 
  parts 
  of 
  the 
  same, 
  well 
  characterize 
  

   the 
  species, 
  which 
  I 
  dedicate 
  to 
  Dr. 
  Leith 
  Adams. 
  

  

  Stratigraphical 
  position. 
  — 
  Collected 
  from 
  bed 
  No. 
  5 
  at 
  Malta. 
  

  

  4. 
  Psammechintts 
  Duciei, 
  "Wright. 
  

  

  Stratigraphical 
  position. 
  — 
  Should 
  the 
  specimens 
  in 
  this 
  collection 
  

   prove 
  to 
  belong 
  to 
  this 
  species 
  only, 
  it 
  will 
  be 
  seen 
  that 
  P. 
  Duciei 
  

   extends 
  throughout 
  the 
  Maltese 
  beds, 
  excepting 
  Nos. 
  2 
  and 
  3, 
  where 
  

   I 
  have 
  not 
  hitherto 
  found 
  it. 
  The 
  finest 
  and 
  largest 
  specimens 
  are 
  

   from 
  No. 
  1, 
  and 
  chiefly 
  from 
  the 
  ivhite 
  calcareous 
  sandstone, 
  and 
  the 
  

   coralline 
  strata 
  of 
  that 
  bed, 
  where 
  it 
  is 
  plentiful, 
  and 
  associated 
  with 
  

   Cidaris 
  Melitensis, 
  &c. 
  Sometimes 
  fragments 
  of 
  this 
  and 
  Schizaster 
  

   Scillce 
  strew 
  great 
  portions 
  of 
  the 
  white 
  calcareous 
  sandstone 
  strata 
  

   in 
  lines, 
  like 
  the 
  washings 
  on 
  a 
  shore 
  or 
  the 
  deposits 
  from 
  currents. 
  

   It 
  is 
  difficult 
  to 
  find 
  the 
  larger 
  specimens 
  entire 
  ; 
  the 
  largest 
  in 
  this 
  

   collection 
  may 
  be 
  considered 
  one 
  of 
  the 
  best 
  in 
  that 
  respect. 
  There 
  

   is 
  one 
  small 
  specimen 
  from 
  No. 
  4 
  bed, 
  and 
  the 
  only 
  one 
  I 
  have 
  hitherto 
  

   seen 
  or 
  heard 
  of 
  from 
  that 
  formation. 
  In 
  the 
  upper 
  stratum 
  of 
  

   No. 
  5, 
  at 
  the 
  transition 
  between 
  it 
  and 
  No 
  4, 
  small 
  specimens 
  are 
  

   very 
  common, 
  and 
  usually 
  seen 
  associated 
  with 
  Cidaris 
  and 
  the 
  

   Nummulite-like 
  or 
  Foraminiferous 
  -looking 
  body 
  sent 
  along 
  with 
  the 
  

   collection 
  of 
  Cidaris. 
  A 
  specimen 
  showing 
  this 
  distribution 
  is 
  sent, 
  

   also 
  a 
  fragment 
  showing 
  two 
  teeth. 
  I 
  have 
  not 
  examined 
  the 
  deeper 
  

   portions 
  of 
  No. 
  5 
  ; 
  I 
  cannot 
  in 
  consequence 
  be 
  certain 
  that 
  the 
  Urchin 
  

   extends 
  downwards 
  in 
  that 
  formation. 
  It 
  may 
  be 
  that 
  its 
  rarity 
  in 
  

   No. 
  4 
  is 
  owing 
  to 
  that 
  bed 
  not 
  having 
  preserved 
  it 
  so 
  well 
  as 
  the 
  

   Limestones. 
  All 
  the 
  specimens 
  I 
  have 
  as 
  yet 
  found 
  in 
  No. 
  5 
  were 
  

   very 
  small 
  compared 
  with 
  the 
  largest 
  from 
  No. 
  1. 
  (A. 
  L. 
  A.) 
  

  

  5. 
  Psammechintts 
  Scillj3, 
  Wright. 
  

  

  Echinus, 
  Scilla, 
  Corp. 
  Mar. 
  tab. 
  xiii. 
  fig. 
  1 
  and 
  tab. 
  xix. 
  fig. 
  3. 
  

  

  Test 
  globular, 
  flattened 
  at 
  the 
  base 
  ; 
  ambulacral 
  areas 
  moderately 
  

   wide, 
  with 
  two 
  rows 
  of 
  marginal 
  tubercles 
  closely 
  set 
  together, 
  and 
  

   a 
  few 
  smaller 
  tubercles 
  disposed 
  without 
  much 
  regularity 
  in 
  the 
  

  

  