Chaetophora 213 



In brooks, chiefly attached to pebbles and rocks. 



Massachusetts : Middlesex Fells, July (449). 



New York : Bronx Park, May (372) ; Van Cortlandt Park, 

 May (603). 



New Jersey : Hudson Heights, May (434) ; Demarest, Oc- 

 tober (507). 



Though sometimes appearing to be very closely related to C. 

 elegans, nevertheless, in general this species is very distinct from 

 that form. It usually has a darker green color, and firmer more 

 resistant gelatinous substance ; in fact it is often a difficult matter 

 to separate or crush the closely packed filaments. Though size is 

 a very variable quantity, in general the filaments of C. piriformis 

 are more slender than those of C. elegans, the branches are always 

 erect, and the terminal branchlets usually less numerous. This 

 species appears to be less inclined to grow in quiet waters ; we 

 have nearly always found it in a strong current. 



3. Chaetophora attenuata sp. nov. 



Colonies globose or slightly verrucose, solitary, 2-5 mm. in 

 diameter, bright green, involved in dense and very resistant gelat- 

 inous substance ; filaments dichotomously or trichotomously 

 branched from the base, always erect and subparallel, not fascic- 

 ulate at summit ; terminal branchlets finely pointed or setiferous ; 

 cells of the main filament 5-5.5 p in diameter, 5-10 times as long; 

 branch-bearing cells broad and often bifurcated at the top {pi. jp). 



On rocks and pebbles at the edge of ponds. 



Connecticut: Plymouth, reservoir, September (491, type). 



New Jersey : Greenwood Lake, September (466). 



This species, like C. pisiformis, possesses a more resistant gelat- 

 inous investment, and a stricter habit of branching than C. clcgans, 

 but its filaments are much finer and more attenuated than those 

 of either of the other species. It is characterized by great regularity 

 in its branching above, and by abundant rhizoid development, 

 rhizoids being pushed out even below the palmelloid basal cells. 

 This appears to be a summer form, for all traces of it disappear 

 before the end of October, and none appeared in the spring up to 

 the middle of May. 



It is a curious fact that CliactopJwra pisiformis and C. attenuata 

 are at times infested by rotifers, while C. elegans seems never to be 



