﻿100 
  Messrs. 
  H. 
  J. 
  Carter 
  and 
  R. 
  Hope 
  on 
  a 
  new 
  

  

  unrecognized 
  by 
  those 
  who 
  have 
  written 
  on 
  the 
  Spongida 
  

   since 
  that 
  time, 
  as 
  lately 
  proved 
  by 
  a 
  specimen 
  brought 
  to 
  

   my 
  notice 
  by 
  Mr. 
  Robert 
  Hope, 
  F.Z.S., 
  of 
  Cumberland 
  

   Terrace, 
  London, 
  and 
  which 
  he 
  found 
  at 
  Hastings. 
  So 
  con-' 
  

   vinced 
  am 
  I 
  now 
  by 
  his 
  preparations 
  and 
  arguments 
  of 
  the 
  

   desirability 
  of 
  giving 
  this 
  British 
  form 
  of 
  Microciona 
  pos- 
  

   sessing 
  a 
  tricurvate 
  with 
  spiniferous 
  extremities 
  a 
  distinct 
  

   name 
  and 
  description, 
  that 
  I 
  have 
  much 
  pleasure 
  in 
  joining 
  

   him 
  in 
  thus 
  publicly 
  correcting 
  the 
  misconception 
  and 
  sup- 
  

   plying 
  the 
  deficiency 
  above 
  mentioned. 
  

  

  Jt 
  is 
  not 
  pretended 
  that 
  the 
  presence 
  of 
  a 
  tricurvate 
  with 
  

   spined 
  extremities 
  in 
  Microciona 
  is 
  a 
  peculiarity, 
  for 
  the 
  form 
  

   was 
  described 
  and 
  delineated 
  by 
  the 
  late 
  Oscar 
  Schmidt 
  in 
  

   1870 
  as 
  forming 
  part 
  of 
  the 
  spiculation 
  of 
  a 
  species 
  of 
  Suberites, 
  

   which 
  he 
  therefore 
  called 
  Suberites 
  arciger. 
  The 
  specimen 
  

   was 
  very 
  small, 
  not 
  being 
  more 
  than 
  4 
  centimetres 
  in 
  diameter, 
  

   and 
  came 
  from 
  the 
  coast 
  of 
  Greenland 
  (' 
  Grundziige 
  atlant. 
  

   Spong.-Faun.' 
  p. 
  47, 
  Taf. 
  v. 
  fig. 
  6). 
  

  

  The 
  next 
  delineation 
  and 
  description 
  of 
  this 
  form 
  of 
  tri- 
  

   curvate 
  was 
  published 
  by 
  myself 
  in 
  1876 
  as 
  a 
  part 
  of 
  the 
  

   spiculation 
  of 
  a 
  species 
  of 
  Dictyocylindrus, 
  Bk., 
  which 
  I 
  called 
  

   I), 
  abyssorum. 
  The 
  specimen, 
  which 
  was 
  dendriform 
  and 
  

   branched, 
  came 
  from 
  the 
  Atlantic 
  Ocean 
  between 
  the 
  north 
  

   of 
  Scotland 
  and 
  the 
  Faroe 
  Islands, 
  and 
  was 
  about 
  3| 
  inches 
  

   high 
  (" 
  Deep-sea 
  Sponges 
  and 
  their 
  Spicules, 
  dredged 
  by 
  

   H.M.S. 
  'Porcupine/" 
  'Annals,' 
  1876, 
  vol. 
  xviii. 
  p. 
  232, 
  

   pis. 
  xii. 
  and 
  xv. 
  figs. 
  3 
  and 
  25 
  respectively). 
  

  

  In 
  1874 
  also 
  Dr. 
  Bowerbank 
  illustrated 
  and 
  described 
  a 
  

   species 
  of 
  Isodictya 
  under 
  the 
  name 
  of 
  /. 
  coriacea 
  (Mon. 
  

   Brit. 
  Spong. 
  vol. 
  iii. 
  pi. 
  lxxvi. 
  figs. 
  7-12, 
  p. 
  228), 
  in 
  which 
  

   this 
  form 
  of 
  tricurvate 
  was 
  present 
  ; 
  but 
  he 
  failed 
  to 
  notice 
  

   the 
  spined 
  extremities, 
  as 
  may 
  be 
  seen 
  by 
  Mr. 
  Stuart 
  Ridley's 
  

   emended 
  description 
  of 
  the 
  same 
  specimen 
  (now 
  in 
  the 
  British 
  

   Museum) 
  under 
  the 
  name 
  of 
  Dirrhopalum 
  coriaceum 
  

   (Journ. 
  Linn. 
  Soc, 
  Zoology, 
  vol. 
  xv. 
  p. 
  481, 
  pi. 
  xxix. 
  

   figs. 
  3-7), 
  an 
  example 
  of 
  which 
  I 
  also 
  found 
  here 
  (Budleigh- 
  

   Salteiton, 
  S. 
  Devon) 
  several 
  years 
  ago, 
  even 
  before 
  Dr. 
  

   Bowerbank's 
  description 
  (/. 
  c.) 
  was 
  published, 
  growing 
  on 
  

   the 
  surface 
  of 
  SteUetta 
  aspera 
  in 
  a 
  cake-like 
  form 
  about 
  an 
  

   inch 
  in 
  diameter 
  and 
  half 
  an 
  inch 
  thick 
  in 
  the 
  centre, 
  as 
  the 
  

   specimen 
  which 
  I 
  still 
  possess 
  shows. 
  To 
  this 
  sponge 
  now 
  

   Messrs. 
  Ridley 
  and 
  Dendy 
  have 
  very 
  properly 
  given 
  Schmidt's 
  

   generic 
  name 
  Plocamia 
  ( 
  l 
  Challenger 
  ' 
  Report, 
  1887, 
  p. 
  158, 
  

   pi. 
  xxix. 
  fig. 
  9 
  and 
  pi. 
  xxxi. 
  fig. 
  1). 
  

  

  In 
  1874 
  I 
  described 
  the 
  specimen 
  of 
  Microciona 
  possessing 
  

   the 
  tricurvate 
  with 
  spined 
  extremities 
  to 
  which 
  I 
  have 
  alluded 
  

  

  