OLPIDIUM. 203 



small globular germ-cells with a darker nucleus and a single 

 long cilium. 



Length of cells, 56-64 //. 



On the oogonia of various Oedogonia. 

 Plate CV, figs. 20-22, Chytridia seated on oogonia. 



CHYTRIDIUM MINUS, Lacost et Suring. 



Cells subgiobose or somewhat oblong, pale yellow with a 

 low operculum, base wide above, penetrating the membrane 

 of filamentous algae, and terminating in a point. Length 

 6-14 jw, without operculum and basal root-like process. 



Frequent on algse of various kinds. 

 Plate CV, figs. 17, 18, different forms of C. minus. 



CHYTRIDIUM GLOBOSUM, A. Br. 



Cells usually perfectly spherical, single or numerously 

 aggregated; devoid of operculum, of radicals, of elongated 

 neck, but possess two or more orifices ; apparently of two 

 varieties, a larger and smaller form. 



Parasitic on algse of various kinds. 



Syn. RMzophydium globosum, A. Br. 



Plate CV, fig. 14, the most frequent variety ; figs. 11, 12, 

 13, a larger form from New Jersey. 



Genus 69, OLPIDIUM, A.Br. 



Cells globose or subgiobose, parasitic, epiphytal or endophytal, 

 not rooting ; mouth vertical, elongated into a cylindrical tube. 



OLPIDIUM AMPULLACEUM, A.Br. 



Epiphytal, gregarious, globose, small, sessile, rarely pedi- 

 cellate, tubular, mouth erect, cylindrical, nearly as long as 

 the cell, terminating in a conical apiculus. 



Diameter of cells, 6-8 yw. 



Frequent on filamentous algse. 

 Plate CV, fig. 7, cells on a filament of Oedogonium. 



OLPIDIUM INTESTINUM, A.Br. 



Entophytal, usually gregarious in the interior of larger 

 plants, depressedly globose, extending at the apex into a 

 tubular neck which is globosely dilated in the middle; 



