﻿52 
  

  

  G. 
  E. 
  TINE 
  OK 
  THE 
  WEDLOCK 
  POLYZOA. 
  

  

  Ascodictyon, 
  Nicholson 
  and 
  Etheridge, 
  jun., 
  

   Ann. 
  & 
  Mag. 
  Nat. 
  Hist. 
  June 
  1877. 
  

  

  Gen. 
  Char. 
  u 
  Organism 
  composite, 
  parasitic, 
  adherent 
  on 
  foreign 
  

   bodies, 
  composed 
  of 
  numerous 
  calcareous 
  cells 
  or 
  vesicles, 
  the 
  walls 
  

   of 
  which 
  are 
  perforated 
  by 
  a 
  greater 
  or 
  less 
  number 
  of 
  microscopic 
  

   foramina, 
  but 
  which 
  possess 
  no 
  single 
  large 
  aperture. 
  The 
  cells 
  

   may 
  be 
  united 
  almost 
  directly 
  by 
  the 
  intervention 
  of 
  short 
  tubular 
  

   necks: 
  or 
  they 
  may 
  be 
  disposed 
  in 
  clusters 
  connected 
  with 
  one 
  

   another 
  by 
  hollow 
  filamentous 
  tubes, 
  which 
  usually 
  anastomose, 
  and 
  

   which, 
  in 
  some 
  cases, 
  at 
  any 
  rate, 
  are 
  likewise 
  perforated 
  by 
  micro- 
  

   scopic 
  pores 
  " 
  *. 
  

  

  This 
  genus 
  was 
  established 
  by 
  the 
  authors 
  for 
  species 
  found 
  in 
  

   the 
  Devonian 
  formation 
  of 
  America 
  and 
  the 
  Carboniferous 
  of 
  Scot- 
  

   land. 
  I 
  have 
  not 
  seen 
  the 
  Devonian 
  species, 
  and 
  I 
  rely 
  on 
  the 
  

   general 
  accuracy 
  of 
  Prof. 
  Nicholson's 
  details 
  with 
  regard 
  to 
  these. 
  

   With 
  our 
  own 
  Carboniferous 
  species 
  I 
  am 
  very 
  familiar. 
  Since 
  

   having 
  the 
  plcntitude 
  of 
  washed 
  shales 
  supplied 
  by 
  Mr. 
  Maw, 
  I 
  have 
  

   been 
  able 
  to 
  examine 
  some 
  hundreds 
  of 
  specimens 
  on 
  stems 
  of 
  

   crinoids, 
  broken 
  shells, 
  and 
  corals. 
  This 
  circumstance 
  has 
  helped 
  

   me 
  to 
  understand 
  and 
  work 
  out 
  many 
  biological 
  details 
  the 
  narration 
  

   of 
  which 
  would 
  be 
  out 
  of 
  place 
  in 
  a 
  general 
  paper 
  like 
  the 
  present. 
  

   I 
  accept 
  the 
  genus 
  of 
  Prof. 
  Nicholson 
  and 
  Mr. 
  Etheridge 
  ; 
  and, 
  

   so 
  far 
  as 
  I 
  am 
  able 
  at 
  present, 
  I 
  give 
  below 
  descriptions 
  of 
  the 
  

   various 
  species 
  found 
  within 
  a 
  very 
  limited 
  range 
  in 
  these 
  shale- 
  

   washings. 
  

  

  Figs. 
  1 
  & 
  2.— 
  Ascodictyon 
  stellatum, 
  Nicli. 
  Sf 
  Ether., 
  var. 
  

   siluriense, 
  Vine, 
  

  

  Several 
  rosettes, 
  showing 
  the 
  habit 
  of 
  the 
  colonies, 
  together 
  with 
  a 
  few 
  of 
  the 
  

   filaments: 
  X 
  24. 
  

  

  4. 
  ASCODICTTOK 
  STELLATUM, 
  Var. 
  SILTJEIENSE. 
  (FigS. 
  1 
  & 
  2.) 
  

  

  Messrs. 
  Nicholson 
  and 
  Etheridge 
  characterize 
  their 
  Ascodictyon 
  

   stellatum 
  as 
  follows 
  : 
  — 
  

  

  * 
  Nicholson 
  and 
  Etheridge. 
  work 
  cited 
  above, 
  p. 
  463. 
  

  

  