38 



The size of the cells, the bright-aerviginous color .and particularly 

 the vertical arrangement of the cells, so as to form a dense stratum, 

 separate this species from all other described forms, 

 . PHORMIDIUM, Ktz.— P/^. ?nembranaceum, Ktz. , and Ph, interrupt 

 tu?n, Ktz. Two forms collected by F. H, Hosford in Vermont- 



MICROCOLEUS, Desmaz.— tT/. lacusiris, Rab. Hab. Pond, 



Atsion, N. J, 



LYNGBYA, Ag.— Z. aestuarii, Jurg. Hab. Ponds of submarine 



waters, Dennisville, N. J. 



RIVULARIA, Ag. — R. radians, Thur., var. ininutula, Kirch. Col- 

 lected by Dr. Hobbe in a lake in Minnesota, July, 1880. He reports 

 .it " very abundant, covering the surface of the lake for a consider- 

 able extent. The natives consider it to be grass-seed washed into 

 the lake." The thalli are in size like small poppy-seeds. Cohn de- 

 scribes a similar appearance on a lake in Silesia. He says that the 

 thalli appear In masses resembling the spawn of fishes. 



ISACTIS, Th\xr,—LJiuviatilts, Rab. Collected by F. H. Hosford, 

 Vermont, from pebbles and stones on the borders of lakes. Found 

 also in Green Pond, N. J. 



SCYTONEMA, Kg.—Sc. gracile, Ktz, var. tolypotrichoides, 

 n, var,^ Witt.: Pseudoramuli plerumque solitarii; heterocystae et 

 basilares et interjectae. Diam. fil. 13/^ — 21/i. Hab, In Morris 

 Pond, N. J. 



Represented inWittrock and Nordstedt's " Exsiccatae," No. 389. 



Sc, cinct7i7taiay Thur. This plant has been previously noticed as 

 Lynghya cincinnata^ it having appeared to the describer of the species, 

 Kutzing, of Germany, to belong to that genus. Thuret found the 

 same plant in France, but called it a Scytone?na. Kirchner collected 

 it in Silesia, and finding the generic character of neither Lyngbya nor 

 Scytonema^ made a new genus — Chrysosiigma^to include this partic- 

 ular plant. Each quotes the plant of the other authors, implying 

 that they did not see correctly. The fact is that all were right, but 

 that each saw the plant in different conditions. I find the plant in a 

 pond near by. Sometimes it may be olassed with one, and then 

 again with the other genus. Its usual appearance is that of a Lyng- 

 bya, but sometimes it assumes the form under which Kirchner saw 

 it, and at other times it is a perfect Scytonema, with yellow heterocysts 

 and single and double branches. 



CALOTHRIX, Ag. — C. radiosa, Ktz., ysiX. fuscescens, Ktz. Col- 

 lected by F, H. Hosford in Vermont. C, Orsmianum, Thur. New 

 Jersey and Pennsylvania. 



. . Calothrix HosFORDii, ;/. ^/.^C. strato olivaceo, trichomatibus 

 aggregatis, laete aerugineis, subdichotomo-fasciculato-pseudoramosis, 

 flagelliformibus, in basi crassis (.001") in apice hyalinis longe cus- 

 pidatis, leniter flexuosis; articulis diametro triplo-quadruplo breviori- 

 bus; vaginis crassis, distinctelamellosis; in basiluteis sursum achrois 

 hyalinis; cellulls perdurantibus basalibus singulis subhemisphericis, 

 trichomatibus diametro subaequalibus. Diam. trich. s. vag. .0004'' 

 .0005"; vag. ad .001" — .0012", Collected by F. H. Hosford in Ver- 

 mont. 



This plant is nearest to Calothrix {SchizosipJion^ Ktz.) Meneghi- 



