(Edogoniaeeae 



vegetative cells, OE. punctato-striatum De Bary has tlje entire filaments fur- 

 nished with spirally arranged granules, and (E. iii-rnn/iin-uni De Bary possee> 

 a remarkable terminal oogonium. The oospores are either globose, elliptic l,-i] 

 or ovoidal, and the cell-wall may be smooth, ridged, spiny, punctate, scrolm-u- 

 late or reticulate. Sometimes the oogonia are plicated as in (E. platygynum 

 Wittr., or they may possess a transversely disposed ring of conical projections 

 as in (E. Itzigsohnii De Bary (fig. 12 C). In some species the supporting cell 

 of the oogonium is much swollen, as in (E. Borisianum (Le Cl.) Wittr. and 

 (E. lautumiiinim Wittr. (fig. 13 C and D). 



Rather less than half the known species are dioecious nannan- 

 drous, and most of the remainder are monoecious. 



Genus Bulbochsete Ag., 1817. The plants of this genus are 

 branched and every branch usually terminates in a long hollow 

 bristle with a swollen base. The vegetative cells widen upwards, 

 most of them carrying a laterally placed bristle, and they do not 

 reach the same relative length as those of (Edogonium. The 

 oogonia are generally terminal on short lateral branches ; and, with 

 few exceptions, the supporting cell of the oogonium is divided by 

 a transverse septum, the position of which is fairly constant for 

 any one species. In the dioecious nannandrous species the andro- 

 sporangia are commonly situated on the apices of the oogonia. 

 The plants occur as branched tufts, more often fixed than in the 

 preceding genus, and they possess a quantity of enveloping mucus, 

 affording a home for numerous Diatoms and often Desmids. 



There are about 14 British species, of which B. nana Wittr. (diam. of 

 vegetative cells 1015 ^; fig. 15 C) is the smallest and B. gigantea Priugsh. 

 (diam. of vegetative cells 24 32 /*) the largest. No doubt many more species 

 will be found if searched for, but in the greater part of the British Islands 

 fructiferous specimens are relatively scarce. There is great variability in the 

 form and size of the vegetative cells in the different species, and also in the 

 comparative size and length of the bristles. The genus is not so abundant as 

 (ffdagonium, and all the species prefer very still waters. 



Most of the species of this genus are dioecious nannandrous. 

 Few species are monoecious, and dioecious macrandrous species are 

 as yet unknown. 



\V. A. 



