124 FRESII-WATER A L G yE OF THE UNITED STATES. 



Spli. serratiini, Bailey. 



Spli. cL'lluli.s diauietro duplo brevioribus, profuiule ct acute exeisis, arete conjunctis; lobis 

 utrinqae cuspidatis, paulum conniventibus ; istbmis nullis ; vagina crassa. (R.) 



Syn, Sph. serralum, Bailey, Micros. Observation. Smitbsonian Contributions, 1850. Cum 



icone. 

 jga6.— South Carolina ; Georgia ; Florida ; Bailey. 



"Joints broader tban long, deeply notebed or divided into two transverse portions with acute 

 projecting ends, wliicb give a serrated outline to the cbaiu." Bailey. 



Genus HYALOTHECA. 



CelluliE brevffi, cylindricaj, medio non profnnde con.strictfe, a latere disciformes, in fila confervacea 

 sine istbmis arete conjuuctoe et vagina mucosa ampla acbroa inclusae. Massa cbloropbyllosa in 

 quaque seraicellula 4-8, 5-10 radiata. 



Cells sbort, cylindrical, not profoundly constricted in the middle, disciform in the end view, 

 closely united without intervening isthmuses into a confervoid filament, which is inclosed in an 

 ample mucous sheath. Chlorophyl masses in each cell 4-8, 5-10 radiates. 



H. disilliens, (Smith) Breb. 



H. fasciis prselongis ; cellulis oblongo-quadrangularibus, diametro sub-dnplo brevioribus, inter- 

 dum ante divisionem sul)8equalibus, angulis nonnihil rotundatis, plerumquc medio obsolete 

 constrictis, sffipe baud constrictis. 



Z>iam— 0.00089"— 0.00008". (R.) 



Syn. — U. disilliens, (Smith) Breb. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 152. 



Uab. — South Carolina; Florida; Rhode Island; Bailey. Rhode Island (S. T. Oluey), 

 Thwaites. Pennsylvania ; Wood. 



Filament very long, cells oblong, quadrangular, about one-half as long as broad, sometimes before 

 division as long as broad, angles somewhat rounded, mostly obsoletely constricted in the 

 middle, often not constricted. 



Remarhs. — The specimens which I have identified as i?. c^mZZtms, agree with 

 the various figures and descriptions of the European form, in every thing except 

 that in many cases there is no constriction whatever in the centre of the cell, and 

 when the constriction docs exist, it is never so pronounced, as some of the descrip- 

 tions indicated. The plant is very common about Philadelphia, growing in springs 

 and ditches. 



Fig. 12, pi. 12, represents this part of a filament of this species. 



H. miicoiiia, (Mert.) Ehrb. 



H. fasciis confervaceis, minus fragilibus ; cellulis quadrangularibus, diametro nequalibus vel 

 suba;qualibus, medio non constrictis, ad utrumque fiuem (auuuliformi-bicarinatis) bideutatis. 

 (R.) Species mihi ignota. 



Z)iam.— 0.00073"— 0.0008". (R.) 



Syn. — Gloeoiorium miicosum, Hassal, Fresh "Water Algte, p. 346. 



H. mucosa, (Mert.) Eiirb. Rabenhorst, Flora Europ. Algarum, Sect. III. p. 132. 



//»6._Rhode Island ; (S. T. Olney) Thwaites. 



Filament scarcely fragile, mucous sheath very broad ; joints about as broad as long, not con- 

 stricted, but having at one of the ends a minute bideutate projection on each margin, the 



