202 FRESH-WATER ALG^ OF THE UNITED STATES. 



APIOCYSTIS BRAUNTANA, Naeg. 



Thallus pear-shaped, pallid green ; the cavity filled up by 

 gelatinous matter, in which are imbedded the gonidia, at 

 first few, increasing in number with age up to 1,600. Diam- 

 eter of thallus, 20-100 ^ or more. Height nearly twice as 

 much. Internal gonidia average 7-8 yu. 



Smaller pools or ponds, attached to water plants ; have 

 had some good specimens, but never in large numbers ;'the 

 finest were from Florida. 



Plate CXXIII, fig. 8, two young fronds ; fig. 6, a mature 

 frond; fig. 7, another with cells undergoing segmentation; 

 fig. 9, a larger frond with matured gonidia ; fig. 10, free, 



ciliated gonidia or zoospores. 



* 



Family XV.CHYTRIDIE^J. 



Plants for the most part aquatic, parasitic, epiphytal or endo- 

 phytal, very rarely terrestrial, one or two celled. Cells vesicu- 

 lose, single or gregarious, either innate in the fostering plant, 

 or penetrating its membrane; now and then numerous and 

 densely aggregated ; cytioplasm mucilaginous, most frequently 

 colorless, sometimes colored. Antheridia not yet observed. 



Propagation by oospores or zoogonidia. 



Among a number of forms of plants of doubtful generic posi- 

 tion, perhaps more properly placed with the Lichens or the 

 Fungi. I retain two of the eleven genera recorded by Eaben- 

 horst in his Flora Algarum. The two are the genera Cliytridium 

 and Olpidium, forms which may be retained, and classified with 

 PROTOCOCCOIDE^:. 



Genus 68, CHYTKIDIUM, A. Br. 



Cells globose or somewhat pear-shaped, operculate above ; the 

 root-like base usually innate in various algse, penetrating the 

 membrane of the cells. 



Zoogonidia very numerous, globose, with a nucleus, bearing a 

 single very long cilium, escaping through the orifice of the cell 

 caused by the falling away of the operculuni. 



CHYTRIDIUM ACUMINATUM, A. Br. 



Cells small ovate- pyriform, or balloon -shaped, which pene- 

 trate into the alga3 upon which they grow by a sort of root- 

 like base. The inflated portion of the cell is filled with 

 colorless mucilage from which are formed very numerous 



