
 
        
         
		ii 
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 P l a t e   CCCXXIV. 
 LEATHESIA  TUBERIEORMIS,  A A-.  (7r«y. 
 G e n .  C h a b .  Frond  globose or lobed,  fleshy,  composed  of  jointed,  colourless, 
   dichotomous  filaments,  issuing  from  a  central  p o in t;  their  
 apices, which  constitute  a fleshy  coating  to  the  frond,  coloured  and  
 tufted.  Fructification,  oval  or  pyriform  spores,  concealed  among  
 the  coloured  apical  filaments.  L e a t h e s ia   (-S'. F.  Gray),—in honour  
 of  the Eev.  G. E. Leathes,  a British  naturalist;  and  who  first  com-  
 muuioated this  plant to  Sir J . E. Smith. 
 L e a t h e s ia   tuheriformis-,  fronds  olivaceous,  tuberous, when young  stuffed  
 with  cottony fibres,  at length hollow. 
 L ea th e sia  tuberiformis,  S.  F.  Gray, Nat. A r .  Br.  PI. vol. i.  p.  301.  Harv.  
 Man.  ed.  2.  p. 48. 
 L ea th e sia   marina,  Endl.  3rd Supp.  p.  23.  Kütz.  Sp.  Alg.  p.  543.  J.  Ag.  
 Sp.  Alg.  vol. i.  p.  52. 
 L ea th e s ia   difformis, Aresch.  E/mm. Phyc.  Scand.  p.  154. t.  9.  f. B. 
 COKYNEPHOKA  marina,  Ag.  Syst.  p.  24.  Harv.  in  Hooh.  Br.  Ft.  vol. Ü.  
 p.  390.  Harv.  Man.  ed.  1.  p. 46.  Wyatt,  Alg. Danm.  no.  149.  Grev.  
 Crypt.  Scot.  t. 53.  Harv.  in Much.  FI. Hib.  part  3.  p.  184. 
 CHjETOPHOKA marina,  Lyngb.  Hyd. Dan.  p. 193.  t.  66. 
 N ostoc marinum, Ag. Disp.  p. 45.  et  Syn.  p. 133. 
 ÏBEMELLA  difformis,  Linn.  Syst. Nat.  p. 714.  Huds. FI. Ang.  vol. ii.  p. 565.  
 With.  vol. iv.  p. 82. 
 E iviieakia  tuberiformis,  E.  Bot.  1 .1956. 
 U a b .  Between  tide-marks,  on  rooks,  corallines,  and  the  smaller  Algæ;  
 very  common.  Annual.  Summer  and autumn. 
 Geogb. D is t b .  Atlantic  shores  of  Europe.  Baltic  Sea.  East  coast  of  North  
 America.  Cape of Good Hope,  common,  W .H .H . 
 D esck.  Eronds  when  growing  on  Algæ  scattered  or  solitary,  when  on  rocks  
 usuaUy heaped  together  and much  crowded,  forming wide-spreading tuber-  
 culated  masses,  very variable  in  size,  from that  of  a pea  to  that  of  a large  
 walnut.  When  young,  tbe  interior  of  tbe  tuberous  frond is  stuffed  with  
 weak  empty,  dichotomous,  cobweb-like  fibres,  rising  from  the  base  and  
 radiating  in  all  directions,  hut  as  the  outer  waU  extends,  these  graduaUy  
 perish  and  the  plant  becomes  a hollow ball.  The  lowermost  ceUs  of  the  
 cobwebby  fibres  are  very  long  and  slender  ;  the  upper  ones  become  
 graduaUy  shoider  and  wider,  and  are  two-homed,  or  somewhat hali-moon«  
 shaped, a new  cell springing from each cusp ;  those which adjoin  to the outer  
 wall  are  smaU  and  globose.  The outer  waU is formed of  closely-packed,  
 moniliform,  club-shaped,  vertical  filaments,  lying  in  a  transparent  jelly ;  
 each  filament  formed  of  several  spherical  ceUs  eontammg  olive  granule^  
 pyriform,  sunk  among  the  club-shaped  peripheric  filaments, with 
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