180 Chlorophycece 



Family 6. Hydrodictyacece. Thallus consisting of a coenobium of 

 coenocytes, non-motile, and formed by the apposition of quiescent zoo- 

 gonidia, which may or may not have escaped from the mother-coenocyte. 

 Reproduction sometimes by resting-spores. 



Family 7. Protococcacece (or Autosporacece). Cells solitary, free- 

 swimming, or colonial and associated in minute, more or less definite 

 colonies, easily dissociated or persistent. Multiplication by successive 

 division of contents forming autbspores or autocolonies. Zoogonidia 

 rarely developed. 



Family 8. Palmellacece. Microscopic or macroscopic, gelatinous 

 and indefinite. Cells embedded in a copious gelatinous envelope. 

 Multiplication by division in every direction ; cells often grouped in 

 twos or fours, sometimes with pseudocilia. Colonies free-floating or 

 attached. Zoogonidia with two cilia. 



Family 1. CHJETOPELTIDE^I. 



The Algae included in this family consist of several genera of 

 very obscure affinities, all of which can be distinguished from other 

 members of the Protococcoidese by the presence of setae or bristles. 

 At present they are but little known and the true nature of the 

 bristles has not yet been thoroughly worked out. They are uni- 

 cellular, or aggregates of loose cells, sometimes forming short 

 filaments or flat, pseudoparenchymatous expansions, which in some 

 instances appear to have arisen by a concrescence of short dicho- 

 tomous branch-systems. 



The flat thallus of Chcetopeltis is similar to that found in the 

 Ulvacese, except from point of view of size and the fact that it is 

 attached by the whole of one surface. Chcetosphwridium is a 

 genus which may, perhaps, owing to the short creeping filaments 

 which it sometimes develops and the sheathed bristles, have some 

 relationship to the Herposteiraceae, but its characters are so widely 

 different from those of Herposteiron that it is best kept apart from 

 the Chaetophorales until our knowledge of the genus is augmented. 

 It may be that the resemblances between the Chaetopeltideae and 

 certain of the Chsetophorales, such as they are, are due to a 

 parallelism of modification rather than to a direct affinity. This 

 has been illustrated in the table I have given of the phylogeny of 

 the green Algae on page 30. 



In genera such as Chcetosphceridium and Conochcete multipli- 

 cation certainly takes place by the division of the cells in 

 directions. 



