THE GREEN ALGAE OF NORTH AMERICA 311 



large, with four cilia, which disappear before fertilization by 

 the smaller, pyriform, 4-ciliate spermatozoids. Only one genus. 



HERPOSTEIRON Nageli in Kiitzing, 1849, p. 424. 



Frond microscopic, epiphytic, composed of simple or irregu- 

 larly branched filaments ; cells bearing on the upper surface 

 long, hyaline, inarticulate setae, with bulbous base but no 

 sheath ; chromatophore parietal, with one or more pyrenoids. 

 Asexual reproduction by 4-ciliate zoospores with red stigma, 

 1-4 in a cell ; sexual reproduction by the union of a spermato- 

 zoid and an oospore, both 4-ciliate. 



The forms included under Hcrpostciron and Chaetosphaciidimn 

 have all been included by authors under Aphanochaete, a generic 

 name which apparently must be given up. Detailed reasons for 

 this, as well as an account of the confusion in specific nomen- 

 clature, will be found under Herposteiron in Hazen, 1902. 



KEY TO THE SPECIES OF HERPOSTEIRON. 



i. Cells usually subglobose, 5-10 M diain. i. H. confervicola. 



i. Cells usually subcyliudrical, 4-6 fj. diam. 2. H. vermiculoides. 



1. H. CONFERVICOLA Nageli in Kiitzing, 1849, p. 424; 

 Hazen, 1902, p. 230, PI. XL,II, figs. 5-7; Aphanochaete repens 

 Wolle, 1887, p. 119, PI. CV, fig. 8 ; P. B.-A., No. 762. Creep- 

 ing on various fresh water algae, filaments irregularly torulose ; 

 cells subglobose to nearly cylindrical ; setae more or less fre- 

 quent, about 3-4 p. diam. at base, very slender above, up to 200 

 p. long. Fig. 116. Greenland, Vt. to N. Y., Cal. Europe. 



Probably not uncommon, but visible only on microscopic ex- 

 amination of the host. The setae are not as uniformly produced 

 as in Bolbocoleon and Chaetosphacridium ; often only a small pro- 

 portion of the cells are provided with them. 



2. H. vermiculoides (Wolle) nov. comb.; Aphanochaete 

 vermiculoides Wolle, 1887, p. 119, PI. CV, figs. 9 and 10 ; P. 

 B.-A., No. 161. Cells 4-6 ^ diam., about as long as broad, 

 more or less rounded, single or united in filaments, creeping on 

 larger algae, or attached at two or more points, arched between ; 

 setae few or many, seldom over 50 yu. long, with ellipsoidal base, 

 one, rarely two or three from a cell, often absent. On Zygnema, 

 Hyalotheca, etc. Conn., Pa. 



Nothing being known of the reproduction, the position of this 

 plant is doubtful. The shape of the filaments is singular, often 

 reminding one of a canker worm or measuring worm in motion. 

 Apparently the filament, attached in two places, grows so 



