CRYPTONEMIACE.E. 201 



XXIII. CATENELLA. Grev. 



Frond sub-tubular, constricted at intervals as if jointed, dull purple, membra- 

 nous; the axile portion composed of a lax net- work of anastomosing, longitudinal 

 filaments, emitting to the periphery dichotomous, moniliforra, horizontal branches, 

 whose apices, strongly cohering together, form the membranous Avail of the frond. 

 AWt'i contained in the a.xile net-work of minute, ovate or roundish ramuli. Teira- 

 spores also in small ramuli, lying among the dichotomous pei'ipheric filaments, 

 zonate. 



Small, densely tufted, littoral Alga3 of a dark purple colour. Fronds rising from 

 matted creeping filaments, half an inch to an inch or two in height, vaguely 

 branched, constricted into spurious joints, the branches resembling those of an 

 Opuntia in miniature. The intei"nodes ai'e somewhat tubular, laterally compressed, 

 hollow, except that a very lax net-work of anastomosing longitudinal filaments runs 

 through them. From the exterior meshes of this net issue to all sides horizontal, 

 dichotomous, moniliform filaments, whose apices, strongly glued together by firm 

 gelatine, form the membranous wall of the frond. Conceptades are very rare. Tetra- 

 spores are more frequently found. 



The genus at present consists of two, or perhaps three species, if the form now to 

 be described be entitled to specific distinction. 



1. G ATEJiELL A. pinnata ; densely tufted, rising from creeping filaments; stems 

 erect, once or twice pinnate ; branches horizontally patent ; internodes oblong, the 

 terminal ones acute, all the ramuli divaricate. (Tab. XXIX. B.) 



Hab. On the stems of the mangroves, at high-water mark. Key West, W. H. H. 

 (v. V.) 



Fronds densely tufted, forming wide patches, rising from prostrate surculi, which 

 are attached to the mangrove trunks by lateral discs. These prostrate surculi throw 

 up numerous erect stems, half an inch to an inch high, divaricately pinnate or bi- 

 pinnate ; the branches horizontally patent, opposite or alternate, either naked or 

 having a few secondary branches which are equally patent, the longer ones bearing 

 a few ramuli. Branches moniliform ; the lower internodes sub-cylindrical, the 

 upper compressed, oblong or sub-lanceolate, the ramuli spindle-shaped, acute or sub- 

 acuminate. Colour a dark purple. Substance membranaceous, rigid. It does not 

 adhere to paper. 



Perhaps this is only a variety of C. Opuntia ; but it is much more regularly 

 pinnated than any form of that species known to me, and the internodes are less 

 frequently obovate. 



VOL. IV. — ART 5. D D 



