FRESH-WATER ALG^ OF THE UNITED STATES. 189 



two to five, more or less tumid, single in each sporangium, at maturity reddish or yellowish fuscous, 

 before germination dividing themselves into (mostly four) zoospores. 



Antheridia shortly filiform, 1-2-3-10 articulate, mostly single, either upon the sporangium or 

 vegetation cell. 



Remarhs. — The CEdogoniacece have been by previous writers simply divided into 

 two genera, CEdogonium and Bulhochoite. The plants represented by these two 

 divisions have certainly many characters in common, as in the production of their 

 zoospores and spermatozoids as well as in their peculiar method of cell division. 

 Yet they are so very diverse in some particulars in regard to the latter, as well as 

 in their habit of growth and in the formation of their sporangia, that it has 

 seemed to me that the differences between them were more than suificient to cha- 

 racterize merely genera, and that to each of these groups should be awarded the 

 rank of a sub-family. 



Again, in the old genus of CEdogonium, we have very distinct groups, separated 

 by differences in the most important of all the characteristic portions of the plant — ' 

 the sexual apparatus. These groups are the so-called Moncecious, Oynandrous, and 

 Dicecious CEdogonia; the moncecious division comprising those plants in which one 

 individual gives origin both to the female and male germs; the gynandrous, those 

 species in which the plant that produces the female germ gives origin also to a 

 peculiar zoospore, the so-called androspore, which, after a period of motile life, 

 settles down and develops a dwarf plant, the androedum, in which the spermato- 

 zoids are developed ; and the dicecious group containing species in which the male 

 and female plants are distinct individuals. Dr. Pringsheim states {MorphoJogie der 

 CEdogon., p. 43) that these groups pass into one another, but in my opinion, by his 

 own showing, they are sharply distinct. The nearest approach to such passage is 

 between the first and second groups, and consists simply in the fact that in certain 

 species the androspore when it settles down develops into a one-celled instead of a 

 two or three-celled antheridium. This to me does not seem to indicate a union of 

 the groups, for the essential difference is not in the form or complexity of the an- 

 theridium, but in the circumstance that in the one case the female filament develops 

 a spermatozoid capable of fertilizing the germ, whilst in the other it gives rise to 

 a body which does not possess that power at all, but does have the capability of 

 giving origin to a second plant, in which the spermatozoid is developed. The 

 groups, therefore, appear to be sharply and distinctly definable. 



In the Bulbochcetice but a single genus has as yet been discovered, and this is 

 distinctly gynandrous, but it seems probable that hereafter other plants of this 

 subfamily will be found which are monsecious or disecious, so that we will have 

 in the two subfamilies two parallel groups of genera. 



For the reasons above indicated I have ventured to divide the family into two 

 subfamilies, the one comprising three, the other a single genus. The peculiarities 

 of crrowth, production of zoospores, and sexual development will be found described 

 under the particiilar subfamilies. 



