Mr. G. H. K. Thwaites on Coccochloris Brebissouii. 243 



XXVII . — Description of Coccochloris Brebissonii, a new species 

 of the Palmellese, in conjugation. By G. H. K. Thwaites. 



[With a Plate.] 



Coccochloris Brebissonii, n. sp. Frons saturate-viridis, gelatiuosa, 

 vix cartilaginea, efFusa, nee frustulosa : cellulis subsplisericis 

 vel rotundato-ellipticis, minutissime grauulosis : sporangiis 

 oblougis. 



C Brebissonii occurs upon the perpendicular surfaces of wet 

 rocks, formhig a gelatinous or slightly cartilagmous coating, se- 

 parating very readily from the surface of the rock. It is of a pale 

 green colovir, sometimes slightly reddish. The cells are shortly 

 elliptical with the ends much-rounded, and contain a minutely 

 granulose endochrome of a yellowish green colour. The gela- 

 tinous appendages of the cells cohere to form an apparently 

 homogeneous mass, and are not separately distinguishable as in 

 some species of the genus. The cells when conjugating are at 

 first united by a narrow connecting tube, but this soon enlarges 

 to the width of the cells. The sporangium is of an oblong form 

 and transparent, containing an endochrome somewhat similar to 

 that of the cells, but with the granules much larger. Imme- 

 diately that conjugation of two cells has commenced to take place, 

 their granules of endochrome are observed to have increased in 

 size, and this increase continues until the sporangium is mature. 

 During the formation of the sporangium, the original cell-mem- 

 branes appear to become absorbed, and are not thrown off as in 

 Cylindrocystis Brebissonii. 



Branched threads similar to those represented in my figure of 

 Palmella botryoides, Grev.*, ramify throughout the gelatinous 

 mass of the present species, but only in one instance have I suc- 

 ceeded in tracing a connexion between them and the cells, owing 

 I suspect to the state of maturity of the plant. By watching the 

 species attentively, I hope to be able to observe the early develop- 

 ment of the plant from the contents of the sporangia. 



This well-marked species, which is I believe undeseribed, I 

 have the greatest pleasure in dedicating to the learned French 

 botanist M. de Brebisson, to whose researches we are indebted 

 for the first discovery of species of PalmellecB in a state of con- 

 jugation. 



EXPLANATION OF PLATE VIU. C 



Fig. \. Small portion of Coccochloris Brebissonii, showing the cells and 

 lamif'ying threads. 



— 2. Cells of C. Brebissonii in conjugation. 



— 3. Mature sporangia. All magnified 270 linear. 



* Ann. and Mag. Nat. Hist. Ser. 2. vol. ii. PI. X. 



16* 



