﻿ALCTONARIA. 
  339 
  

  

  present 
  species. 
  In 
  habit 
  these 
  three 
  species 
  are 
  closely 
  similar. 
  

   A 
  specimen 
  in 
  the 
  Museum, 
  which 
  is 
  appareutlj^ 
  the 
  type 
  of 
  Bovella 
  

   ramulosa, 
  (jtray 
  (Aun. 
  & 
  Mag. 
  jSTat. 
  Hist. 
  (4) 
  v. 
  p. 
  407), 
  is 
  closely 
  

   allied 
  to 
  E. 
  Jiabcllum, 
  and 
  should 
  stand 
  as 
  EcJiinogorr/ia 
  ramulosa, 
  

  

  EuNICEACEiE. 
  

  

  13. 
  Plexaura 
  praelonga, 
  sp. 
  n., 
  var. 
  typica. 
  (Plate 
  XXXVI. 
  fig. 
  F, 
  

   and 
  Plate 
  XXXVIII. 
  figs, 
  r/, 
  g'.) 
  

  

  Growth 
  upright, 
  approximately 
  in 
  one 
  plane. 
  Common 
  stem 
  ex- 
  

   tremely 
  short. 
  Branching 
  dichotomous 
  ; 
  branches 
  few, 
  almost 
  

   straight 
  : 
  terminal 
  branches 
  150 
  millim. 
  (6 
  inches) 
  and 
  upwards 
  in 
  

   length 
  in 
  adult 
  specimens. 
  Stem 
  and 
  branches 
  cylindrical, 
  either 
  

   nearly 
  of 
  the 
  same 
  diameter 
  throughout 
  in 
  both 
  cases, 
  viz. 
  about 
  

   2-5 
  millim., 
  or 
  ranging 
  from 
  6 
  millim. 
  at 
  base 
  to 
  3 
  millim. 
  at 
  end 
  of 
  

   branches 
  in 
  adult 
  specimens. 
  Cortex 
  approximately 
  smooth, 
  even, 
  

   rather 
  friable. 
  Colour 
  in 
  dry 
  state 
  pale 
  red-brown 
  or 
  dark 
  tawny 
  

   brown. 
  Verrucse 
  small, 
  not 
  projecting 
  from 
  surface, 
  equally 
  distri- 
  

   buted 
  over 
  all 
  parts, 
  5 
  to 
  1 
  millim. 
  apart. 
  Axis 
  tough, 
  flexible, 
  

   black. 
  Cortical 
  spicules 
  : 
  — 
  (i.) 
  Long 
  fusiform, 
  aj^proximately 
  straight, 
  

   tapering 
  to 
  sharp 
  points, 
  with 
  few, 
  scattered, 
  tapering, 
  sharp, 
  simple 
  

   tubercles 
  ; 
  size 
  about 
  -35 
  by 
  -07 
  millim. 
  (ii.) 
  Stout 
  fusiform-cylin- 
  

   drical, 
  covered 
  with 
  low, 
  blunt, 
  compound 
  tubercles 
  ; 
  size 
  about 
  -3 
  by 
  

   1 
  millim. 
  (iii.) 
  Irregular 
  tri- 
  to 
  sexradiate, 
  arms 
  cjlindrical, 
  taper- 
  

   ing 
  to 
  sharp 
  points, 
  with 
  numerous 
  but 
  distinct, 
  prominent, 
  simple 
  

   or 
  compound, 
  pointed 
  tubercles 
  ; 
  maximum 
  diameter 
  of 
  spicule 
  -25 
  

   to 
  -52 
  millim., 
  thickness 
  of 
  arms 
  '042 
  to 
  -1 
  millim. 
  (iv.) 
  Blattkeule 
  ; 
  

   shaft 
  with 
  one 
  or 
  two 
  distinct 
  arms 
  uniting 
  in 
  a 
  moderately 
  stout 
  

   neck, 
  often 
  themselves 
  bearing 
  secondary 
  arms 
  ; 
  the 
  whole 
  shaft 
  is 
  

   covered 
  densely 
  with 
  very 
  prominent, 
  tapering, 
  compound 
  tubercles. 
  

   Foliar 
  portion 
  flattened 
  in 
  one 
  plane, 
  variable, 
  cither 
  approximately 
  ob- 
  

   long 
  with 
  rounded 
  angles, 
  or 
  much 
  drawn 
  out 
  latei'ally, 
  forming 
  angles 
  

   at 
  tliis 
  point, 
  and 
  with 
  a 
  point 
  below, 
  or 
  with 
  the 
  lower 
  edge 
  broken 
  

   up 
  into 
  small 
  lobes 
  ; 
  edges 
  sharp, 
  aiinutely 
  scalloped. 
  From 
  the 
  

   shaft 
  descend 
  on 
  to 
  the 
  foliar 
  portion, 
  sometimes 
  more 
  than 
  halfway 
  

   down 
  its 
  face, 
  one 
  or 
  more 
  narrow, 
  more 
  or 
  less 
  prominent 
  ridges, 
  

   tajiering 
  so 
  as 
  gradually 
  to 
  disappear 
  ; 
  or 
  the 
  place 
  of 
  each 
  ridge 
  is 
  

   taken 
  by 
  one 
  or 
  more 
  rounded 
  prominences 
  ; 
  both 
  ridges 
  and 
  pro- 
  

   minences 
  are 
  smooth 
  ; 
  length 
  of 
  spicule 
  about 
  "5 
  millim., 
  breadth 
  of 
  

   Blatt 
  -3 
  millim. 
  

  

  Hah. 
  Port 
  Curtis, 
  5-11 
  fms., 
  bottom 
  sand 
  and 
  shells 
  ; 
  Port 
  Deni- 
  

   son, 
  4 
  fms., 
  bottom 
  rock. 
  

  

  Obs. 
  Two 
  dry 
  specimens, 
  the 
  one 
  from 
  which 
  the 
  larger 
  external 
  

   measurements 
  were 
  taken 
  being 
  largely 
  decorticated, 
  occur, 
  also 
  

  

  Plexaura 
  ma}- 
  be 
  open 
  to 
  doubt 
  ; 
  in 
  its 
  spiciiliitiou 
  it 
  agrees 
  with 
  Plexaurella 
  as 
  

   limited 
  by 
  Verrill 
  (Proc. 
  Ess. 
  Inst. 
  vi. 
  p. 
  42) 
  ; 
  but 
  L)r. 
  Khinzinger 
  does 
  not 
  

   state 
  explicitly 
  whether 
  the 
  axis 
  is 
  simply 
  horny 
  or 
  wlidher 
  it 
  contains 
  tlie 
  

   carbonate 
  of 
  lime, 
  by 
  the 
  presence 
  of 
  wliich 
  Kolliker 
  distinguishes 
  the 
  genus 
  

   from 
  Plexaura. 
  

  

  z2 
  

  

  