WISCONSIN PHYTOPLANETON 181 



.Branchlets abundant, opposite, scattered in basal portion, dense in dis- 

 tal, oi:'-y slightly narrower than the branch from which they arise and 

 with terrmual cell conical or setiferous. Lower cells of main branch 

 swollen %--4 times as long as broad, with a girdle-like chloroplast in 

 median portion. (Tychoplanktont). 



Main branches 14r-16.5 /* broad; branchlets 6-7 p broad. 



Mendota (rrr), Wild Goose (rrr). 



Family APHANOCHAETACEAE. 



Thallus epiphytic, generally upon other algae, creeping in habit and 

 composed of simple or irregularly branching filaments that taper from 

 the center to short, narrow terminal cells that do not end in terminal 

 setLe;. Central cells of filament spherical to spherical-cylindrical ; those 

 towards the end cylindrical with straight or convex sides; terminal 

 cells conical. Cells generally bearing one or more long, hyaline, un- 

 septate setae with swollen bases. Chloropast parietal, completely fill- 

 ing the cell, or gridle-like and in the median portion; generally with 

 ID ore than one pyrenoid. 



Asexual reproduction by tetraciliate zoospores or aplanospores. 



Sexual reproduction heterogamous, by the fusion of tetraciliate zoo- 

 gametes that are markedly different in size. 



The family contains the single genus ApJianochaeie whose characters 

 are those of the family. 



APHANOCHAETE VERMICULOIDES Wolle. PI. 50, Fig. 8. 



Preshw. algae of U. S. 119, pi. 105, figs. 9-10. 1887. 



Eerposteiron hyalothecae Hansgirg. G. M. Smith, Trans. Wis. Acad. Scl., 

 Arts, & Lett. 18 2 : 560. 1916. 



Filaments but slightly branched and confined to the peripheral por- 

 tion and twisted around or arched from the gelatinous envelope of 

 UyalotJieca filaments. Cells cylindrical, with straight or convex sides 

 and containing a single chloropJast with 1^4 pyrenoids. Setae very 

 sparse, rarely more than five on any filament. (Tychoplanktont). 



Cells 4^-6 p broad ; 5-12 /* long. 



Beaverdam (rr). 



All other species of the genus grow directly upon the cells of the 

 substratum but the wide gelatinous envelope of the Hyalotheca is in 

 this case sufficiently firm to support the Aphanochaete. The alga has 

 the appearance of an arching worm crawling along the filament. 



