254 Minnesota Algae 



Collins, Holden and Setchell. Phyc. Bor.-Am. Fasc. 5. no. 218. 1896. 

 Collins. Preliminary Lists of New England Plants. — V. Marine Algae. 

 Rhodora. 2:41. 1900; Phycological Notes of the late Isaac Holden. — II. 

 Rhodora. 7:223. 1905. 



Plate XVI. fig. 4. 



Plant mass caespitose, brownish red or violet; filaments 2-3 mic. in 

 diameter, 1-3 mm. in length, erect, fasciculate; sheaths thin, uniform; 

 trichomes constricted at the joints; cells shorter than their diameter; cell 

 contents granular. 



Maine. On cliffs at high water mark. Eagle Island, Penobscot Bay. 

 July 1892. (Collins). Rhode Island. (Collins). Connecticut On stones. 

 Fresh Pond. November. (Holden). 



Genus CALOTHRIX Agardh. Syst. Algar. 24. 1824. 



Plant mass consisting of penicillate tufts or a soft velvety expansion; 

 filaments simple or slightly branched; heterocysts basal or intercalary, ab- 

 sent in a few species; gonidia basal, seriate. 



I Heterocysts not present. C. Juliana 



II Heterocysts present. 



I Plants living in salt water 

 (i) Heterocysts basal 

 A Plants fasciculate or penicillate, parasitic 



a Filaments 12-15 mic. in diameter C. confervicola 



b Filaments 21-29 m'c- in diameter C. consociata 



B Plants caespitose, often growing on rocks 

 a Filaments 8-12 mic. in diameter; cell contents violet 



C. fusco-violacea 

 b Filaments 10-18 mic. in diameter; cell contents olive green 



C. scopulorum 

 c Filaments 9-15 mic. in diameter; cell contents olive green 



C. contarenii 

 d Filaments 15-20 mic. in diameter; cell contents olive green 



C. pulvinata 

 e Plants parasitic; filaments 9-15 mic. in diameter, thickened into a 

 bulb at the base; cell contents blue-green 



C. parasitica 

 (2) Heterocysts basal and intercalary 

 A Filaments 9-12 mic. in diameter, scarcely thickened at base 



C. aeruginea 

 B Filaments 15-18 mic. in diameter; false branches solitary 



C. prolifera 

 C Filaments 12-21 mic. in diameter; false branches fasciculate at 

 the apex of the filament C. fasciculata 



