204 SPyPtlDIACE^. V. 



cliflferent lobes ; the younger filaments paniculately branched, with short oblong 

 articulations, tlie mature ones constituting an obconic cluster of spores. These 

 spores, which originate in a cell-division of the articulations, are oblong ; at length, 

 by mutual pressure, angular, separated from one another and held together by a 

 firm gelatine." /. Ag. Sp. Alg. 2, p. 337- 



The tetraspores are formed along the sides of the ramelli ; either from the evolu- 

 tion of new cells or of those of the cortical layer. They are triangularly parted, 



and sessile. 



At present this Order consists of a single genus, separated by Prof. Agardh from 

 the Ceramiacece, on account of the very diiferent structure of its conceptacular 

 nucleus, a character by which it is more nearly related to the Rhodymeniacece than 

 to any other family. The structure of the frond, on the contrary, is identical with 

 that of the former family, so much so, that the species of Spyridia were formerly 

 referred to Ceramium itself. 



Possibly when the conceptacles of BalUa are better known, that genus will form 

 a second in this very distinctly characterised though at present fragmentary Order. 



I. SPYPtlDIA. Harv. 



Frond filiform, terete or compressed, decompoundly much branched, composed 

 of a single, articulated, thick-walled filament, coated externally with a thin layer of 

 small coloured cellules ; and more or less beset with slender, deciduous, articulated 

 ramelli. Conceptacles at the ends of short branches or peduncles, involucrated with 

 a few ramelli, containing within a closed, membranous pericarp, numerous nucleoli 

 of oblong spores. Tetraspores formed along the ramelli, external, sessile, triangu- 

 larly parted. 



The few species of this genus yet known to botanists are all natives of the warmer 

 parts of the ocean. S. filamentosa is the most widely dispersed of any, being found 

 throughout the tropics of the Eastern and Western Hemisphere ; in the Medi- 

 terranean Sea, and along the Atlantic shores of Europe as far as the South of 

 England ; and on the East coast of North America, from Florida as far North as 

 Massachusetts Bay. As might be expected in a plant of such indifference to 

 climate, it varies much both in the luxuriance of its filaments and the amount of 

 their ramelli ; also, though in a less degree, in the primary ramification. Our var. 

 refracta almost looks like a species. 



1. '^¥YR\mK fdamentosa, Harv. ; frond filiform, decompoundly branched ; branches 

 alternate, repeatedly divided, ramellose ; ramelli scattered, hair-like, articulate, end- 



