﻿( 
  307 
  ) 
  

  

  XVIII. 
  — 
  On 
  some 
  remarkable 
  Marine 
  Invertebrata 
  new 
  to 
  the 
  British 
  Seas. 
  By 
  

   Edwaed 
  Forbes, 
  F.R.S., 
  F.L.S., 
  Professor 
  of 
  Botany, 
  King's 
  College, 
  London 
  ; 
  

   and 
  J. 
  Goodsir, 
  F.R.S.S.L. 
  and 
  E., 
  Professor 
  of 
  Anatomy, 
  University 
  of 
  Edin- 
  

   burgh. 
  

  

  (Read 
  20th 
  January 
  and 
  3d 
  February 
  1851.) 
  

  

  The 
  animals, 
  either 
  wholly 
  new, 
  or 
  new 
  to 
  Britain, 
  described 
  in 
  the 
  following 
  

   communication, 
  were 
  taken 
  during 
  a 
  yachting 
  cruise, 
  with 
  our 
  indefatigable 
  

   friend 
  Mr 
  Macandrew, 
  among 
  the 
  Hebrides, 
  in 
  the 
  month 
  of 
  August 
  1850. 
  

   During 
  this 
  voyage, 
  which 
  lasted 
  three 
  weeks, 
  a 
  series 
  of 
  observations 
  were 
  con- 
  

   ducted 
  by 
  means 
  of 
  the 
  dredge 
  and 
  the 
  towing-net. 
  Not 
  a 
  single 
  new 
  form 
  of 
  

   testaceous 
  mollusk 
  was 
  procured 
  ; 
  our 
  exertions 
  were 
  amply 
  rewarded, 
  however, 
  

   by 
  the 
  discovery 
  of 
  several 
  remarkable 
  Ascidians 
  and 
  Radiata, 
  some 
  of 
  them 
  so 
  

   curious 
  in 
  themselves, 
  and 
  so 
  important 
  in 
  their 
  zoological 
  bearings, 
  that 
  we 
  have 
  

   thought 
  it 
  desirable 
  to 
  lay 
  an 
  account 
  of 
  their 
  characters 
  and 
  anatomy 
  before 
  the 
  

   Royal 
  Society 
  of 
  Edinburgh. 
  

  

  The 
  most 
  remarkable 
  of 
  them 
  is 
  the 
  largest 
  of 
  compound 
  Ascidians 
  yet 
  dis- 
  

   covered 
  in 
  the 
  Atlantic. 
  Its 
  nearest 
  described 
  ally 
  is 
  the 
  genus 
  Diazona 
  of 
  

   Savigny, 
  between 
  which 
  animal 
  and 
  Clavellina 
  it 
  constitutes 
  a 
  link 
  ; 
  one 
  of 
  con- 
  

   siderable 
  zoological 
  importance, 
  since 
  it 
  binds 
  together 
  more 
  closely 
  the 
  truly 
  

   compound 
  Ascidians 
  or 
  Botryllidce, 
  with 
  the 
  social 
  Ascidians 
  or 
  Clavellinidw, 
  which 
  

   latter 
  in 
  their 
  turn 
  pass 
  into 
  the 
  family 
  of 
  Ascidiadce, 
  through 
  the 
  anomalous 
  

   Cynthia 
  aggregata. 
  The 
  discovery 
  of 
  a 
  creature 
  thus 
  filling 
  up 
  a 
  gap 
  in 
  the 
  

   animal 
  series, 
  was 
  of 
  itself 
  a 
  sufficient 
  harvest 
  from 
  our 
  autumn 
  tour 
  ; 
  in 
  this 
  

   instance 
  our 
  pleasure 
  was 
  enhanced 
  by 
  the 
  beauty 
  and 
  singularity, 
  as 
  well 
  as 
  

   novelty, 
  of 
  the 
  remarkable 
  animal 
  we 
  have 
  first 
  to 
  describe. 
  

  

  The 
  Syntethys, 
  for 
  so 
  we 
  propose 
  to 
  designate 
  the 
  Ascidian, 
  presents 
  itself 
  

   in 
  the 
  form 
  of 
  a 
  compact 
  gelatinous 
  mass 
  of 
  half 
  a 
  foot, 
  and 
  sometimes 
  more 
  in 
  

   diameter, 
  and 
  very 
  nearly 
  an 
  equal 
  height. 
  It 
  is 
  affixed 
  to 
  the 
  rock 
  or 
  stone 
  by 
  

   a 
  short 
  slightly 
  spreading 
  base 
  of 
  various 
  breadth, 
  whence 
  rises 
  as 
  an 
  inverted 
  

   pyramid 
  the 
  body 
  of 
  the 
  mass, 
  irregularly 
  circular 
  and 
  slightly 
  lobed, 
  spreading 
  

   out 
  at 
  its 
  summit. 
  It 
  is 
  of 
  a 
  translucent 
  apple-green 
  hue 
  ; 
  the 
  surface 
  is 
  nearly 
  

   smooth. 
  The 
  whole 
  of 
  the 
  expanded 
  disk 
  is 
  thickly 
  studded 
  with 
  individual 
  

   ascidians 
  growing 
  out, 
  as 
  it 
  were, 
  from 
  the 
  common 
  mass. 
  They 
  are 
  arranged 
  in 
  

   irregular 
  rows, 
  with 
  a 
  tendency 
  to 
  concentric 
  order. 
  Each 
  individual 
  measures, 
  

   when 
  full 
  grown, 
  nearly 
  two 
  inches 
  in 
  length, 
  and 
  has 
  the 
  shape 
  of 
  an 
  elongated 
  

   ampulla, 
  with 
  two 
  terminal 
  orifices, 
  set 
  well 
  apart, 
  but 
  not 
  very 
  prominent, 
  and 
  

  

  VOL. 
  XX. 
  PART 
  II. 
  4 
  o 
  

  

  