CEDOGONIACE^E. 65 



Syn. Phyllactidium Australe, Ces. Chaetophora tuberculosa, K. 

 Mueller. 



Occurs in large limestone springs, Northampton County, 

 Pa.; sticks and branches of trees dropped into the water, are 

 often full of this form, as small dark, olive-green promi- 

 nences or tubercles 4-8-20 mm diameter; the larger ones 

 are usually the result of the confluence of two or more 

 smaller ones. 



COLEOCHAETE IKREGULARIS, Prillgsh. 



Thallus bright green, filaments irregularly disposed not 

 parenchymatous and not with any system of order ; articu- 

 lations longer or more frequently shorter than the diameter. 

 Oogonia transversely broadly oval, usually at the ends of 

 branchlets, nude. 



Filaments 15-20 ^ wide. Oogonia diameter 40-45 ^. 



On water plants, leaves dropped in water, etc. This spe- 

 cies assumes many varieties of forms. The one figured was 

 chosen for its good condition of fruit; from a marsh pool, 

 Eastern Pennsylvania. 



Plate LXXII, figs. 15, 16, specimens of Coleocliaete irregu- 

 H,SJ with carpogons. 



Family VLCEDOGONIACEJE. 



Filamentous algae, simple or branched. Monoecious or dioa- 

 cious. Basal cells mostly lobately divided or ending in a discoid 

 foot by which in early stage the plant is attached. Plants articu- 

 late, endowed with a peculiar mode of cell multiplication by 

 transverse division, indicated by transverse striae usually at the 

 apical end of the mother cell. Plate LXXIII, figs. 2, 2, 3. 



The oogonia are developed in the series of vegetative cells, 

 singly or in chains of 2-5 or more, one contiguous to the other, 

 and more or less tumid, with a single oospore in each, first green, 

 then gradually changing to orange, to red or brown, and some- 

 times almost black. The fecundated oospore breaks up before 

 germinating into several, ordinarily four, zoospores. 



Male plants are of two kinds, dwarf and elongated. The dwarf 

 males (nannandres} are found attached to the female plant ; the 

 elongated males are composed of a series of short interstitial 

 cells in an independent filament ; these constitute, the macrandrous 

 forms, and the former the nannandrous forms. Asexual propaga- 



