304 FRESH- WATER ALG^E OF THE UNITED STATES. 



Syu. Oscillatoria lucifuga, Hass. ; Calotlirix luclfuga, Carm. MSS. 



Not infrequent on shaded clay banks ; affects cooler 

 weather; Pennsylvania and New Jersey. No doubt widely 

 distributed. 



Plate CCV, fig. 8, two vertical fascicles greatly magnified ; 

 figs. 9, 10, natural size and usual growth ; figs. 11, 12, single 

 filaments in sheath. 



SYMPLOCA FRIESIANA, (Ag. ) Kg. 



Stratum dull green or blackish, composed of vertical, 

 subuliform fascicles, 10-15 mm high ; trichoines pale blue- 

 greeii, distinctly articulated ; articles about as long as wide. 

 Sheaths rather wide, colorless. 



Diameter of trichonies, 4-6 yu with sheath, 8-12 //. 



The only habitat for this species was discovered by Colonel 

 Macoun, on old wood, Canada. 



Plate COY, fig. 13, a caespitose cluster; figs. 14, 15, two 

 single filaments. The trichomes are often twin in a sheath. 



SYMPLOCA FUSCESCENS, Kg. 



On earth and stones, aeruginous, changes to dull yellowish 

 or brown. Trichomes with age pale olive or yellow-aerugi- 

 nous. In every respect very near 8. lucifuga, except in size ; 

 fascicles only 2 mm high. 



Diameter of trichomes, 2-3 //. 



Plate CCV, figs. 8-12, drawn for 8. lucifuga ; for the 

 present plant, one-half the dimensions may be imagined. 

 Probably it is a mere form of former. 



Genus 102, MICROCOLEUS, Desm. et Thur. 



Trichomes similar to Lyngbya, but two or more, and often many 



included in a sheath, which is primarily closed at the end ; later 

 it opens and sometimes divides into shreads. Sheath ample, 

 colorless, rarely indistinct. Have included under this genus 

 Chthonoblastus, Kg.; Hydrocolewm, Kg.; Dasygloia, Thwaites. 



MICROCOLEUS ( DASYGLOIA ) AMORPHA, (Thwaites; Wolle. 



Forming a thin gelatinous membrane on dripping rocks, 

 amorphous ; sheaths of the trichomes at first thin, then more 

 gelatinous and thicker, cohering. Internal trichomes aeru- 

 ginous, slender, simple. Sheath variable with age. First 

 barely discernible, then twice the diameter of the trichomes. 



