WISCONSIN PHYTOPLANKTON 63 



at base of trichomes, rarely intercalary. Spores, when present, soli- 

 tary and adjacent to heterocysts. 



Reproduction by formation of trichomes and spores. 



GLOEOTRICHIA J. G. Agardh 1842. 



Filaments always in colonies; free-floating or sessile; spherical to 

 hemispherical, tough and leathery to gelatinous, hyaline or colored. 

 Trichomes attenuated to fine hair-like processes at the distal end, en- 

 closed by gelatinous sheaths that are distinct at the base and confluent 

 at the apex. Filaments containing one trichome, but at times showing 

 false branching. Heterocysts spherical to hemispherical, solitary; at 

 the base of the trichomes. Spores cylindrical, solitary, always adjacent 

 to the heterocysts. Vegetative cells convexly disciform to short cylin- 

 drical at base of trichomes, elongate cylindrical with straight sides at 

 apex of trichomes. 



Reproduction by hormogones and resting spores. 



GLOEOTRICHIA ECHINULATA ( J. E. Smith) P. Richter. PI. 11, Figs. 5-6. 



Forschungsbr. a. d. Biol. Stat. zu Plon 2: 31, fl.gs. 1-8. 1894. 



Conferva echinulata J. E. Smith, Eng. Bot., pi. 1378. 1804. 



Rivularia echinulata J. E. Smith, Eng. Bot. index; P. Richter, Forschungsbr. 

 a. d. Biol. Stat. zu Plon 2: 45. 1894; Leminermann, Kryptogamenfl. d. Mark 

 Brandenburg 3, Algen 1: 255, 245, figs. 1, 6. 1907. 



Gloeotrichia pisum Bornet et Flahault (p.p.) non Thuret, Bull. Soc. Bot. 

 France 31: 80. 1884; Ann. Sci. Nat. 7 Ser. Bot. 4: 366. 1886; Trelease, Trans. 

 Wis. Acad. Sci., Arts, & Lett. 7: 124-125 (with fig.) 1889. 



Colonies always free-floating, spherical; up to 2 mm. in diameter. 

 Filaments radially arranged about a common center but becoming ir- 

 regular in arrangement on slight pressure. Sheaths hyaline, homogene- 

 ous, distinct at base, apex frequently confluent with colonial envelope. 

 Trichomes broad at base, attenuated to long, colorless, hair-like pro- 

 cesses. Lowest vegetative cell of trichome hemispherical ; those a short 

 distance from base disciform with markedly convex sides; those in 

 middle of trichome cylindrical ; while the cells in the apical region are 

 elongate cylindrical. Basal cells completely filled with cytoplasm, 

 apical cells with cytoplasm restricted to the median portion. Cell con- 

 tents rarely homogeneous, usually with numerous pseudovacuoles. 

 Heterocysts at base of trichome, spherical. Spores, when present, ad- 

 jacent to heterocysts, elongate cylindrical with rounded ends. 



Cells at base of trichome 8-10 p. broad; at apex 1-2 ^ broad; hetero- 

 eysts 7-10 /* broad ; spores 8-10 p. broad, 40-54 //. long. 



Bass (3) (rr), Bear (3) (rr), Bear Trap (rr), Beaverdam (rr), Birch (2) 

 (se), Birch Island (r), Bone (rr), Carroll (rr), Catherine (sss), Chetac (as), 



