FRESH-WATER ALG^ OP THE tTNITED STATES. 77 



Fig. 4 a, pi. 9, represents a frond of this plant magnified 125 diameters; fig. 4 h, 

 a fragment magnified 460 diameters. 



Professor Bailey, in American Journal of Sciences, vol. iii., new series, states 

 that he has found two species of the genus Stigonema, namely, St. atrovirens, Ag. 

 and St. mammillosum, Ag. ; the former growing on wet rocks at Indian Falls, 

 Putnam County, New York ; the latter at Eound Pond, near West Point. I have 

 no personal knowledge of the genus, but, according to authorities, it belongs to 

 the lichens rather than the algae, apothecia having been detected in various 

 species. 



Class CHIiOKOPHYLIiACE^.^ 



Plantulce aquatic£e vel aerese, imi-, bi-, vel multicellulares, aut singula 

 aut consociatse, familias formantes, 



Vegetatio terminalis vel non terminalis. 



Ramificatio aut nulla aut vera, sed cellularum non divisione, potius 

 prolificatione. 



Cytioderma non siliceum, combustibile, ssepius e stratis successivis 

 compositum, substantiam gelatinosam plerumque liquidam exsudans. 



Cytioplasma chlorophyllosuni, chlorophylli loco nonnunquam erythrino 

 vel substantia oleosa coccinea, carnea aut rufescente coloratum, nucleo 

 (central! vel lateral!) plerumque prseditum, granulls amylaceis rar!ss!me 

 carens. 



Multiplicatio fit cellularum d!v!s!one vegetatlva. Foecundatlo ple- 

 rumque sexualls. 



Propctgatio fit aut oosporls vel zygosporls aut gonldlis tranquilHs vel 

 ag!l!bu8. 



Aquatic or aerial uni-, bi-, or multicellular plants occurring singly, or 

 consociated in families. 



Vegetation terminal or not so. 



Branches either wanting, or if present, true branches, although formed 

 rather by a process of proliferation than division of the cells. 



Cytioderm not sUiceous, combustible, often composed of successive 

 strata. 



Cytioplasm chlorophyllous, sometimes colored by an oily crimson, flesh- 

 colored or yellowish-red substance, in the place of the chlorophyl, gene- 

 rally furnished with a nucleus (either lateral or central), very rarely 

 without starch granules. Growth occurring by the division of the cells. 

 Fecundation generally sexual. 



Propagation taking place by oospores or zygospores, or by tranquil or 

 motile gonidias. 



' The description of tliis Class and Order is that of Prof. Rabenhorst. 



