and Genera of Chlorospermous Algae. 409 



Dr. Harvey thinks these balls arc rather buds than spores, 

 the plant and fructification having great resemblance to Hel- 

 minthocladia among the Rhodosperms. 

 1, Batrachospermum. 



** Sporidia solitary on the branchlets. 

 Fam. 2. Thoreae. 



The frond gelatinous, clothed with a number of byssoid scat- 

 tered ramuli on a cellular stem formed of densely interwoven 

 threads. 



1. Thorea. 



Fam. 3. Lemaneae. 



Frond cartilaginous, solid or hollow, with a cellular peripheral 

 layer and internal tufts of articular branched threads bearing a 

 sporangium. 

 1. Lemanea. 



" The threads are at first precisely like those of a Conferva ; 

 certain joints, however, are protruded from the sides, after the 

 manner of the first division of the threads in Cladophora ; these 

 rapidly increase, both in length and breadth, by means of trans- 

 verse and vertical division ; a cavity is formed in the centre ; the 

 walls are lined with large transparent cells, from which articu- 

 lated threads are sent forth horizontally into the cavity either 

 from every point of the surface or in whorls, insomuch that the 

 structure is almost that of a Cijmopolia or Batrachospermum 

 turned inside out." (Berk. p. 137.) 



" The spores at first vegetate into confervoid, slender, jointed 

 filaments, with long joints containing a spirally-arranged endo- 

 chrome ; at length thick branchlets spring from the cells, which 

 soon acquire rootlets at their base and grow into the perfect 

 frond." (Thwaites, Linn. Trans.) 



Fam. 4. Dasycladeae. 



Frond green, naked or coated with carbonate of lime, having 

 a unicellular simple or branched axis, which is whorled through- 

 out its whole length with articulated ramuli. Spores spherical, 

 developed in proper fruit-cells. 



* Sporidia lateral, at the base of the brancklet. 



1. Dasycladus. (Harvey, Ner. Bor.-Am. 35. t. 41 b.) 



** Sporidia at the top of the branchlet. 



2. Cijmopolia. (Harvey, Ner. Bor.-Am. 33. t. 41 a.) 



Dasycladus has been illustrated in Debes and Solier's memoirs, 

 and is also figured by Kiitzing, and seems rather a compound 

 Conferva and Vaucheria. 



