MICEOCOLEUS. 307 



MICROCOLEUS HYALINUS, (Kg.) Kirch. 



Stratum pale aeruginous, thin, sometimes encrusted, ex- 

 panded, also in solitary fascicles among other algae. Tri- 

 chonies slender, single, or a few in a sheath ; articulations 

 about as long as wide, light aeruginous, sheaths compara- 

 tively wide, colorless, hyaline ; often divided at the ends 

 leaving the impression of a branched filament. 



Diameter of trichomes, 1-1.5 yw; sheaths, 7-10 yw. 



Syn. Schizotlirix hyalina, Kg. 



Plate CCIII, figs. 3, 4, specimens from wet ground, South 

 Carolina, from ponds New Jersey, on Sphagnum; wet rocks, 

 Pennsylvania, etc. 



Not infrequent, but question whether it is a normal, vege- 

 tative condition of a plant. Has the appearance of a faded, 

 dried and contracted form. Measures are often considerably 

 more than quoted, but the character of the plant remains 

 the same. 



MICROCOLEUS EAVENELII, Wolle. 



Forming a stratum on old pasture grounds, dark violet 

 or aeruginous. Trichomes of equal thickness, solitary, or 

 two or three somewhat twisted, in a common sheath, aeru- 

 ginous, changing to golden brown or chestnut color. 

 Sheaths of younger plants close and colorless ; of older 

 plants thicker and firmer, of golden brown color, lamellate ; 

 ends usually empty and coming to a sharp point ; articula- 

 tions subequal, or two to three to a diameter, distinct. 



Diameter of trichomes, 12 yw ; with sheath, about 15 fj. ; 

 sheaths with two or more trichomes proportionately wider, 



Plate CCIII, figs. 12-14, specimens from pasture grounds 

 near Houston, Texas, collected by H. W. Eavenel. 



This form is nearest Hydrocoleuni Brebissonii, Kg. But 

 beside being a larger plant it affects moist ground, not flow- 

 ing river waters. 



MICROCOLEUS HETEROTRICHUM, (Kg.) forma AMERICANA, Wolle. 



Forms a dense gelatinous stratum on large, partially sub- 

 merged, stones in swamps ; deep olive black ; trichomes 

 more or less twisted; two forms in the same sheath. 

 Primarily the diameter of the main internal trichome is 

 12-14 /* ; with sheath, 18-20 /* ; later the sheath widens to 

 25-38 n ; then more slender moniliform trichomes become 

 evident, entwining the larger one. The diameter of the 



