360 Linnean Society. [Feb. 15, 



curvata e latevibus separate lineaqne altera abbreviata utrinque ver- 

 sus angulos posticos. — Long. corp. lin. 5|. 

 Hah. in Insula Hayti, Indise occidentalis. DD. Tweedy et Hearne. In 

 Muss. Soc. Ent. Londin. et Hope. 



February 15. 



The Lord Bishop of Noi-wich, President, in the Chair. 



Charles Cogswill, Esq., M.D., was elected a Fellow. 



Read a memoir " On the early stages of the Development of Le- 

 manea Jiuviatilis , Agardh." By G. H. K. Thwaites, Esq. Commu- 

 nicated by the Rev. M. J. Berkeley, F.L.S. 



Mr. Thwaites attributes the neglect of the early condition of this 

 conferva to its having been confounded in this stage with Trente- 

 pohlia pulchella ^. chalybea, Harv., with which it is frequently found 

 growing intermingled. He states that it may be observed in great 

 abundance towards the end of November, covering the surface of 

 stones witli a uniform, dark olive, somewhat villous coating, and 

 adhering with great pertinacity by means of its minute roots. The 

 structure of the plant at this early stage is found to consist of nu- 

 merous conferva-like filaments, of about a line in length and spa- 

 ringly branched. Each filament is about yyL_th of an inch in dia- 

 meter, and consists of a single row of cells, which are from 4 to 6 

 times longer than wide, and have a blue-green endochrome arranged 

 in a spiral manner, except in the terminal cells, where it is more 

 abundant and gives them a darker colour. This stage Mr. Thwaites 

 regards as analogous to the confervoid filaments which form the pri- 

 mordia of a moss, or to the mycelium of a fungus ; and he adds that 

 Kiitzing has described and figured the early condition of Lemanea 

 torulosa, Agardh, as very similar. 



From a cell near the base of this conferva-like structure a branch is 

 given off, which at first differs apparently from the ordinary branches 

 only in its cells being much shorter. This little branch increases 

 rapidly in length and thickness from the multiplication of its cells 

 by fissiparous division ; and to enable it to acquire a firmer support, 

 a number of roots are given off from its base (in the same manner 

 as in the phyton of a moss), and it is thus enabled to attach itself 

 aud maintain an independent existence. From this period it gra- 



