140 University of California Piiblications in Botany [Vol. 8 



(or cysts) ; non-sexual spores either motile (zoospores, zoogonidia, or 

 planospores) or non-motile (aplanospores, formed inside the wall of 

 the original cell, and akinetes where the outer wall of the original cell 

 is included in the spore formation) ; zj^gotes formed either from 

 isogametes (either isoplanogametes, i.e., both equal and motile, or 

 isoaplanogametes, i.e., both equal and non-motile) or from aniso- 

 gametes (or heterogametes, i.e., unlike gametes) ; germination of the 

 zygote various. 



Chlorophyceae Kuetzing, Phyc. Germ., 1845, p. 118 ; Wille, in 

 Engier and Prantl, Natiirl Pfianzenfam., 1 Th., 2 Abt., 1897, p. 24; 

 Oltmanns, Morph. und Biol, der Alg., vol. 1, 1904, p. 133; West, 

 Algae, vol. 1, 1916, p. 126. Chlorospermeae Harvey, in Mackay, Fl. 

 Hibern., part III, 1836, p. 163, Genera So. African Plants, 1838, 

 p. 403. 



Harvey seems to have been the first to propose the classification 

 into green algae, brown or olive-green algae and red algae, as now 

 usually adopted, and coined the names Chlorospermeae, Melano- 

 spermeae and Rhodospermeae. In his Chlorospermeae, he included 

 also what are now separated under Myxophyceae, very few of which, 

 however, were known to him. Kuetzing was the first to use the 

 ending phyceae, but his Chlorophyceae included both the Chloro- 

 spermeae and Melanospermeae of Harvey and is consequently very 

 different in its content from that of more recent writers. 



There is some difference of opinion, even at present, as to the exact 

 content of the Chlorophyceae. It has seemed best to follow West 

 (1916, p. 126) in including also the Conjugatae as well as the groups 

 with zoospores, although the decision assumes no practical importance 

 in the present account, since none of the Conjugatae is properly 

 marine. 



The great majority of the marine Chlorophyceae are inhabitants 

 of the littoral belt, a few descending to the upper portion of the 

 sublittoral belt, while those occurring in deeper waters are, so far 

 as the extra tropical portions of the Pacific Coast of North America 

 are concerned, very few indeed. 



The great majority of the Chlorophyceae are either subaerial or 

 inhabitants of strictly fresh waters, so that a number of the important 

 groups are not found in the salt waters. Unfortunately for this 

 account, also, the strictly tropical waters of the Pacific Coast of North 

 America are, as yet, unexplored, and little is known as to the occur- 

 rence, or non-occurrence, of the more complex forms of the Codiaceae, 



