HALIMEDA. 229 



fibres were succulent filaments, which crossed and branched ir- 

 regularly. M. Schweigger adds, that the stracture of the cel- 

 lular tissue is decisive of the vegetability of this coralline. Its 

 parenchyma is foi-med of vesicular pentagonal or hexagonal 

 cells, a structure similar to that in plants, but which has not 

 been observed in any animal. Link has himself examined the 

 H. opuntia, and his observations agree in general with those of 

 Schweigger, but, using a higher magnifier, he has perceived that 

 the fibrous tissue fonning the middle layer of the articulations 

 and uniting them together, is entirely composed of bi^anched 

 leaflets, as in the Laver or Ulva. These leaflets form a mem- 

 bi'ane which receives the vesicular cells, for the cells, which are 

 rarely angular, are not in contact, and consequently do not con- 

 stitute the membrane that contains them. The contrary being 

 the fact in plants of a higher order, the Halimeda has no affi- 

 nity to them, but its structure approaches that of the Algae so 

 near as to entitle us to say, that the Halimedeas are compound 

 ulvae, in the same way that the Fuci may be considered to be 

 compound Confervse. The calcareous deposition is eff"ected in 

 the cells in the interior of the coralline, or on the two surfaces 

 of the innermost layer. lAnk in Ann. des Sc. Nat. n. s. part. 

 Bot. ii. p. 322. 



1. H. OPUNTIA, " branches trichotomously divided, the 

 joints waved on the margin, and kidney-shaped.'''' 



Coralliiia opuntioides minor, Petiv. Pterogr. tab. 20, fig. 19. 

 Articulated Coralline of Jamaica, Ellis, Corall. 53, pi. 25, fig. 6, 



B, B, 1. 

 Corallina opuntia, PaZ/. Elench. 420. Lin. Syst. 1304. Ellis and 



Soland. Zooph. 110, pi. 20. fig. h. Esper, Corall. tab. 1. Bosc, 



Vers, ii. 73. Schweig. Beobacht. 43, tab. iii. fig. 20 — 24 ; and 



tab. viii. fig. 73. Edin. Phil. Journ. i. 220. 

 Flabellaria opuntia. Lam. Anim. s. Vert. ii. 345 : 2de edit. ii. 528. 



Blainv. Actinol. 551, pi. 65, fig. 4. Thompson in Ann. Nat. 



Hist. V. 254. 



