MICROCOLETTS. 305 



Most frequently only one in a sheath, but sometimes two or 

 three. 



Diameter, without sheath, 10-13 ^. 



Unlike the European, "coalescing in a solid gelatinous 

 mass as large as a swan's egg;" this plant forms a thin, 

 olive, or dark aeruginous green membrane, skin-like, on 

 trickling rocks, Glen Onoko, Pennsylvania. Have gathered 

 it here, always in the same condition, a number of succes- 

 sive summers. 



Syn. Dasygloia amorplm, Thwaites ; Microcoleus variecolor, 

 Kirch. ; Schizothrix variecolor, Bab. 



Plate CCIV, figs. 1, 2, several simple filaments ; figs. 3-6, 

 young plants spirally coiled, gradually opening as they de- 

 velop into forms as figs. 1, 2 ; figs. 7, 8, 9, sheaths with one 

 or more trichomes included. 



MICROCOLEUS PULVINATUS, Wolle. 



Thallus large cushion-like, often 6-8 or more inches in 

 diameter ; about two inches thick, somewhat hollow in the 

 center ; dark olive brown ; gelatinous membranaceous ; 

 readily lifted from the water without breaking. Trichomes 

 one, two or three in a sheath. 



Diameter of trichomes, 5-6 yu ; sheaths, 12-20-30 /-/. 



The thalli, of all possible sizes from one to ten inches in 

 diameter, are attached to stones and grasses, looking like 

 boulders in the bottom of a mill race with rapidly running 

 water; Bamber, New Jersey. This peculiar growth oc- 

 curred on repeated visits to the locality in different years. 



Plate CCIV, figs. 13, 14, two small thalli; figs. 10-12, 

 sheaths with one, two, and three trichomes. 



MTCROCOLEUS TERJRESTEIS, Desm. 



Stratum more or less expanded, deep blue-green, or steel 

 blue, or changing to olive and then to a brownish red ; niem- 

 branaceous, mucilaginous; trichomes equal, collected in 

 filiform fascicles, sometimes much elongated, extruding 

 from the opening of a common sheath in a penicillate man- 

 ner, articulations equal in length and breadth. May be 

 divided into two varieties, viz.: 



1. repens, Kg., trichomes, 5-6 ju in diameter, ends of 

 sheath open. 



2. Vaucheri, Kg., trichomes, 4-5 yw, ends closed or torn. 



