368 BOTANICAL GAZETTE [November 



three layers, the middle thick, perforated, and orange colored; on 

 germination giving rise to zoospores. Whole plant 200-2000 p 

 high, its main axis 40-100 fi in diameter. 



Found but once, and on an aphid in a water culture made from soil taken 

 from the bottom of an almost dry inland pond near Ithaca, N.Y. 2 



Axi primario ovato ad cylindricum, basi divisionibus rhizomatoideis 

 numerosis, sursum copiose dichotome v. subdichotome ramoso; ramosis 

 intervallis constrictis; pseudo-septis perforatis intra ramulorum basimformatis; 

 zoosporangiis ovalibus ad sphaeroidea, 50-63X40-52 /a, papillas dehiscentes 

 paucas ferentibus; zoosporis ovalibus, 12X8 /x, cilio plerumque simplici 

 ornatis; sporangiis perdurantibus, rotundatis, basim versus graditim angus- 

 tioribus et truncatis, 45X35^, zoosporis foventibus. 



Hab. Ad aphid in aqua, Ithaca, N.Y. 



Summary 



1. The plant resembles in general the other species of the genus. 

 Its mycelium is definitely constricted, which fact, it seems, definitely 

 places the genus in the family Leptomitaceae. 



2. It possesses peculiar perforated pseudo-septa which are 

 formed at the constrictions, and which in a way are comparable 

 to the "cellulin rings" of other members of the Leptomitaceae. 



3. Zoosporangia are provided with a number of papillae of 

 dehiscence distributed over the surface, which are formed as the 

 result of the gelatinization of small circular areas of the wall. The 

 resulting plug is made up of two distinct parts, the inner of which 

 forms a vesicle into which the zoospores escape at the time of their 

 discharge. 



4. The zoospores possess a large centrally located subtriangular 

 mass of apparently some reserve food substance, probably proteid 

 in nature, at whose base is located the nucleus. They are typically 

 uniciliated, with the cilium in direct relation to the nucleus. 



5. Resting sporangia possess a three-layered wall; the. outer 

 and inner layers thin and hyaline; and the middle thick, perforated, 

 and orange colored. After a period of rest of several weeks, 

 germination takes place by the formation of zoospores. 



2 During May and June 1911 this species appeared several times in water c - 

 tures made from two garden soils one-fourth mile apart near Urbana, 111. As it was 

 found in soil collections made at different times and parts of the gardens, it was 

 evidently not rare in those particular locations. ' 



