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



and sometimes bear secondary branches. The cells are granu- 

 late, and grow in a single series, rarely in two; they are 

 distinct or, sometimes, continuous. Heterocysts are frequent. 

 The sheaths of the branches, usually colorless, are always 

 thinner than those of the primary filaments. Spores are 

 formed from the ordinary vegetative cells. The plants grow 

 in fresh and salt waters. 



CLASS II. BACILLARIE.E (DIATOMACEiE). 



We have, as yet, given no attention to the Diatoms, and 

 they are, therefore, omitted from this report. 



CLASS III. HETEROKONT^E. 



The Algae of this class are unicellular, multicellular, or 

 colonial, appearing as rounded single cells, filaments, or large 

 colonies. The cell walls are usually very thick, and contain 

 many chromatophores of a yellow-green color, without pyre- 

 noids or starch. The ordinary asexual reproduction is by 

 means of zoogonidia, which are pear-shaped bodies furnished 

 with one long and one short cilium. Non-motile spores are 

 also sometimes found with thick walls. 



Sexual reproduction takes place by fusion of two similar 

 motile gametes which probably resemble the zoogonidia in 

 having two cilia. Since these gametes are alike they are said 

 to be isogamous. This class contains only a single order. 



ORDEfR CONFERVALES. 



The various forms are divided into two families, as 

 follows : 



Family i. botrydiace;e. Plant body large, globose. 

 Family ii. tribonemace^. Plant body unicellular or 

 filamentous. 



family i. botrydiace^:. 



Each plant is globose, attached by rhizoids to the damp 

 earth ; the chromatophores are numerous and the reproduction 

 varied. This family contains only one genus, which we have 

 not vet found in Connecticut. 



