232 SPH^ROZYGA. 



In ditches of the marsh to the south of Frindsbury canal, near Graves- 

 end, in great abundance in June, 1832, Rev. M. J. Berkeley. Shirehamp- 

 ton, near Bristol, Mr. Thwaites. " Forming small, roundish, gelatinous 

 masses, floating amongst different species of Lemna in fresh water, but 

 probably within the influence of the tide, and also amongst Enteromorpha 

 inteslinalis, and even within the frond in brackish water. The plant is at 

 first of an olive-yellow, gradually assuming a greener tint, and when dried, 

 of a deep verdigris. Very gelatinous, delicately branched ; the branches 

 very flaccid. Under a high magnifier, the whole plant is evidently com- 

 posed of gelatine, in the centre of which runs a single, monilifonn fila- 

 ment, following the ramifications, and in its progress curling to and fro 

 repeatedly across the thread ; the joints being nearly globular. The speci- 

 mens from the interior of Enteromorpha are paler, and have often longer 

 joints amongst the globular ones.'' Berk. A most interesting and beauti- 

 ful plant, forming a clear link between Nostoc and Sphcerozyga. I am in- 

 debted to Mr. Berkeley for specimens. 



II. SPH.EROZYGA. Ag. [Plate 27, D.] 



" Filaments free, simple, moniliform, consisting of a series 

 of ordinary cells interrupted here and there by a cell of a 

 different kind (connecting -cell, or heterocyst) which is gene- 

 rally of a larger size, and often ciliated." Thw. Spores 

 formed from the ordinary cells. Name, from a-paipa, a globe, 

 and wyo?, a yoke. The name Anabaina, applied to this genus 

 by Bory, and adopted in our first edition, is pre-occupied for 

 a genus of Euphorbiaceae, by A. de Jussieu. 



1. S. Carmichaelii, Harv. ; " spores large, oblong, twice 

 or thrice as long as broad, commencing to be formed from 

 the cells most distant from the ciliated connecting one." Tliw. 

 Harv. Phyc. Brit. t. cxiii. A. Belonia torulosa, Carm. in 

 Hook. Br. Fl. 2, p. 379; Harv. Man. ed. 1, p. 167. Ana- 

 baina marina, Breb. 



On decaying marine Algae about half-tide level. Appin, Capt. Carmi- 

 chael. Menai Bridge and Barmouth, &c., Mr. Ralfs. Shirehampton, Mr. 

 Thwaites. " In the beginning of autumn, vast quantities of the filament- 

 ous Algae (Dictyosiphon, Ectocarpus, &c.) are detached from their places 

 of growth, and deposited here and there along the shore in extensive fleeces. 

 When these fleeces begin to decay, the Sphcerozyga makes its appearance 

 in the form of a very thin gelatinous pellicle, of a vivid green colour, 

 spreading over the surface of the decaying mass. The pellicle is made up 

 of straight, brittle, slightly moniliform filaments, one fourth of a line in 

 length, and tapering at both ends. The intervals between the striae are 

 considerably longer than their diameter, and the green matter becomes at 

 length consolidated into elliptical sporidia, of a brownish colour, beginning 

 at the middle of the filament.'' Carm. 



2. S. Thwaitesii, Harv. ; spores elliptical, once and a half 

 as long as broad, commencing to be formed from the cells 



