132 NEMATOPHYCE^. 



RIonostroma Wittrockii. Born. Notes Alg. p. 176. 



Thallus membranaceous, gelatinous, bright green (18 mill.) 

 oblong, pedicellate, at first saccate, then open at the summit, 

 margin becoming irregularly lobed. The adult plant becomes 

 sessile, and is attached by apart of its surface, when mature the 

 fronds are large (8 cent, diarn.), the lobes plicate, elongated 

 and rounded, cell angular, subquaternate, in section of thallus 

 rounded, chlorophyllose body occupying about half the cell. 



In salt or brackish water. 



Perhaps hardly claiming a place in this work, as it is more truly a 

 marine species. 



Plate LL, fig. 8. Portion of a frond X 200. Fig. 9, 10, sections of 

 frond X 200. Fig. 11, zoogonidia X 300. Fig. 12, germinating X 200, 

 after Bornet. 



Monostroma bullosum. Wittr. Mon., p. 28, is the Tetraspora 

 ballosa of this work, see j;. 16, plate vi., fig. 1. 



FAMILY II. SPH^BROPLBAOEJB. 



Threads simple, with terminal vegetation, very long, articu- 

 late, articulations cylindrical, by spurious septa nmltilocular. 

 Chlorophyllose mass distributed in annular bands, which enclose 

 from 3-7 starch vesicles. 



Propagation by oospores after sexual fecundation, very 

 numerous in the cells, at first green, then red ; enclosed in a 

 stellate sporoderm. 



GENUS 57. SFHJEROPLSA. Ag. (1824.) 



Characters the same as given above for the family, which 

 consists but of one genus. 



The following is an abstract of a memoir on SphtBroplea annulina, by 

 Cohn (in the "Ann. des Sci. Nat.," 1856, p. 187), describing the process 

 of fructification : " The structure of the resting-spores is very singular. 

 They are red spherical bodies, from one 120th to one 100th of a line in 

 diameter, and formed of two hyaline membranes, the interior of which 

 is intimately connected with its plastic contents, whilst the exterior is 

 loose and elegantly plaited. These plaits or folds are so arranged that 

 they meet at their two poles ; often, however, they are very irregular 

 in shape and direction, especially in the larger spores. 



" In germination the resting-spores undergo several modifications. They 

 become granular and change to a dull brown red, and a more transparent 

 circle appears in their centre. Frequently the red matter changes to 

 green before the germination, and this change of colour is gradual, 

 proceeding from the circumference to the centre of tho cavity. At 

 length the whole of the plastic contents divides into two, then into four 

 or eight bodies, which burst the double envelope and disperse in the 

 water as so many zoospores. 



