IO CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



CLASS VII. RHODOPHYCE^E (Red Algae). Con- 

 taining a reddish coloring matter known as phycoerythrin. 

 Mostly marine. 



In the study of the fresh-water Algae we are concerned 

 chiefly with the first five of these classes, the other two being 

 practically confined to salt water, although a few of them, as 

 noted at the end of this report, are inhabitants of fresh water. 



CLASS I. CYANOPHYCEAE. 

 ( Myxophyceae, Schizophyceae, or Blue-green Algae). 



The class Cyanophyceae is unquestionably the lowest class 

 of the Algae, many of the species resembling the Bacteria. 

 Their most conspicuous characteristic is the manner in which 

 the greater number of the genera grow in gelatinous masses 

 or strata. They are largely filamentous, though some are 

 unicellular. Some of them grow wherever there is moisture, 

 as on wet rocks, stones, and trunks of trees. Some of the 

 filamentous genera form thick, felt-like coverings upon moist 

 earth and stones. Many of the Cyanophyceae are provided 

 with heterocysts, which are cells of lighter color and often of 

 greater size than the other cells of the filament. The hetero- 

 cysts are almost always solitary on the filaments, and their 

 use is not known. 



The unicellular and simple colonial genera multiply princi- 

 pally by repeated cell-division, which may occur in every direc- 

 tion or in certain directions only. Asexual reproduction of 

 the large forms takes place in a variety of ways. In some 

 families certain vegetative cells enlarge and form spores ; in 

 others the contents of the cells divide into a number of small 

 spores. The Hormogoneae reproduce by hormogones. These 

 are short filaments arising from the mother plant, which break 

 away and form new plants. Sexual reproduction is unknown. 



Some of the Cyanophyceae unite with Fungi to form 

 Lichens, in which case they lose much of their distinctive 

 character. 



A few of the Cyanophyceae, of the family Oscillatoriaceae, 

 are distinguished for their power of spontaneous movement, 

 which is generally slow, oscillating or gliding. Many of this 



