TOLYPOTHRIX. 263 



SYMPHYOSIPHON CRUSTACEUS, Kg. 



Forming a crustaceous, black coating on moist rocks; 

 filaments in clusters irregularly united. Articulations 

 somewhat constricted at joints; cytioplasm dull aeniginous. 

 Sheath somewhat indistinct ; tapering from the base to the 

 apex, yellowish brown, smooth, uneven ; heterocysts single 

 or rarely twin, elliptic, pale orange. 



Diameter of filaments, 2-3 /* ; sheath at base, 6-7 yw ; at 

 apex, 3-4 yw. 



Not infrequent, wet cliffs, Pennsylvania. 



Genus 88, TOLYPOTHRIX, Kg. 



Trichomes furnished with a sheath, branched. Ramifications 

 solitary (very rarely geminate), originating where the continuity 

 of the trichome is interrupted by a heterocyst ; the trichome 

 below it breaking through the sheath and continuing its growth ; 

 in consequence there is normally, one, or more than one hetero- 

 cyst directly above the brauchlet. 



TOLYPOTHRIX DISTORTA, Kg. 



Caespitose floccose, bright aeruginous, now and then 

 becoming pale ; trichomes and pseudo- branches very loosely 

 interwoven, internally aeruginous, sometimes apparently 

 continuous, sometimes distinctly articulate ; joints equal, to 

 a little shorter than the diameter ; sheaths close, colorless ; 

 heterocysts subglobose or oblong, solitary or two or three 

 together, usually colorless. 



Diameter of trichomes, 12-17 yw. 



Forma magma, Wolle, has a diameter of 33 yw. Differing from 

 the type-form in size only. 



Syn. Calothrix distorta, Ag. ; Oscillaria distorta, Ag. ; Conferva 

 distorta, Mueller. 



Pond waters. Forma magma, East Charlotte, Vermont. 

 The typical form is widely distributed. 



Plate CLXXX, figs. 1, 2, 3, the usual form ; fig. 4, Forma 

 magma. 



TOLYPOTHRIX AEGAGROPILA, (Kg.) Kirch. 



Thallus spherical, about the size of peas (diagnosis of 

 Kg. and Kirch, has diameter an inch or more) floating in 

 masses, greenish olive (primarily aeruginous) trichomes and 

 pseudo- branches loosely interwoven, internally pallid blue- 



