vol.i] Setchell— Gardner. — Algce of Northwestern America. 199 



Gloiotrichia Pisum Thuret. 



On leaves of Potarnogeton, in ponds of fresh water. Whidbey 

 Island, Wash.. X.L.G.. Xos. 459! 463!; near Seattle, Wash., 

 Professor T. C. D. Kincaid, No. 767! 



The specimens are all young and there are no spores, but 

 there is Little doubt as to the determination of the species. 



CHLOROPHYCEA. 



We have used the name Chlorophycea?, in the broad sense to 

 include all those alga? which have no coloring matter in addition 

 to the chlorophyll. This includes the group of the Conjugata?, 

 which differs so much from the others in cell structure 

 and in the possession of non-motile gametes that it is generally 

 separated. Similar opinions may be held as to some other 

 families under the Chlorophycea?, so that it seems best to reserve 

 one term for all the grass-green alga?. In the treatment of this 

 group, we have omitted all reference to the Desmidiacea?, since 

 from their number and the difficulties of study, they are not 

 usually taken up by the general student. We have, in general, 

 followed the classification proposed and carried out by Wille 

 (1890-1891) in Engler and Prantl, departing from it only in 

 some minor cases. For species, we have used for reference 

 DeToni's account (1889), and such special papers as were par- 

 ticularly concerned in special cases and mentioned in the body of 

 the text. 



In the Chlorophycea? we find that the majority of species are 

 either cosmopolitan, or at least are common to the colder waters 

 of the Northern Hemisphere. We have not constructed a table 

 of species showing comparative distribution, since in the imper- 

 fection of our knowledge such a table would be more or 

 less misleading. We find, however, that we know now that it is 

 quite within the bounds of reason to expect to find any species of 

 this group which occurs in the North Atlantic, also in the North 

 Pacific. There are, probably, some species restricted to each 

 district, but we are as yet very uncertain whether those which 

 we now consider to be characteristic of the North Pacific, may 

 not later be found also in the North Atlantic and the reverse. 



