CRENOTHRIX. 293 



joints. Heterocysts subglobose, rarely hirsute ; spores 

 oblong-cylindrical, 2-3 times longer than broad, distinctly 

 granular. 



Diameter of cells, about 4 ^ ; spores, about 10 jw. 

 On dripping rocks, and on wet ground, Pennsylvania. 



CYLINDROSPERMUM COMATUM, Wood. 



Growing on the ground, forming a gelatinous stratum of 

 an aeruginous color ; filaments nexuous, equal, intricate, not 

 spiral ; joints shortly cylindrical, equal to or more than 

 twice as long as wide; mostly separated; pale aeruginous, 

 obscurely granular, terminal cells subglobose ; spores oblong- 

 cylindrical, about twice as long as wide, granular, yellowish- 

 brown ; membrane thick, distinctly granulate. 



Diameter of filaments, 3 // ; spores, 10 //. 



There appears to be but little to commend this plant for a 

 new species, but in a supplementary remark the author adds, 

 "The terminal cells are remarkable for being abundantly 

 provided with long, flexible, hair-like processes, upon the 

 ends of which are minute globular bodies. These appendages 

 are so minute as to make it difficul^ to determine their struc- 

 ture." If these hair-like processes are anything more than 

 the result of the contraction of the gelatinous covering of 

 the cell, they will constitute a good distinguishing feature. 



Plate CXCIX, fig. 16, a copy of Wood's figure. 



SECTION V. OSCILLARIE.E. 



Simple filaments with or without sheath, singly or forming 

 extended strata, without heterocysts and without spores, not 

 terminating in a hair-point. 



Multiplication takes place, first by hormogonx, parts of internal 

 trichomes which slide out of the end of a sheath, or which are 

 scattered by the dissolution of the sheath ; each small part, con- 

 sisting of but a few cells, quickly starts a new growth, develops 

 new filaments like the one from which it was separated ; this 

 applies particularly to Oscillaria, Lyngbya and tiymploca; secondly 

 by means of gonidia developed usually in the cells of the parent 

 plant. 



Genus 99, CBEXOTHRIX, Conn. 



Filaments distinctly articulate, colorless, surrounded by a 

 gelatinous envelope. 



Propagation by means of microgonidia, and macrogonidia ; 

 the former developed by the longitudinal division of the cytio- 



