50 The Ohio Naturalist. [Vol. X, No. 3, 



Monochytriuni presumably has as great an opportunity for the 

 dispersal of its spores in dewdrops and spattering rain as has 

 Synchytrium. The writer is therefore led to expect that when 

 the zoospores of Monochytriuni are observed they will be found 

 to be amoeboid rather than flagellate. 



For a summary of the most important points in the life 

 history of Monochytrium a condensed technical description ma)' 

 be offered. The type and only known species I propose to name 

 in honor of Professor F. L. Stevens who has made notable con- 

 tributions to the cytology of the lower fungi. 



Monochytrium gen. nov. 



IVIycelium nullum, plasmodium rotundatum; sporae perdurantes 

 30-50/<, globosae, ortae a copulationis zoosporarum intra cellulas 

 matricis, binucleatae, exosporio crasso, paene levi non echin- 

 ulata; zoosporangia circa 70/jt, formata a zoosporis sine copula- 

 tione, unum a quoque plasmodio, sine membrana, sine coUo; 

 zoosporae numerosissimae, 2.5/i, moto ignoto. 

 Intra cellulas epidermicas aut h}-podermicas aut raro chlorenchy- 

 matas plantarum viventium. 



Monochytrium stevensianiim sp. nov. 



Characteribus generis. Intra cellulas foliarum petiolorumque 

 Ambrosiae artemisiifoliae in Raleigh, Carolina boreali; Stevens & 

 Hall Julio 1908. 



The slides containing the type specimens are deposited in the 

 herbarium of the Ohio State University. With them are index 

 cards giving the lo'cation of the cysts draWn, in vernier readings 

 of the Spencer Lens Company's mechanical stage No. 490 with 

 the verniers set to read 30 ancl 90 respectively when the aperture 

 in the centering slide accompanying the instrument occupies the 

 optical axis of the microscope. The originals of all the figures 

 mav therefore be qtiickly found with any microscope equipped 

 with a No. 490 mechanical stage, or with any mechanical stage 

 with a vernier reading to tenths of millimeters for after one is found 

 and the differences in reading between stage No. 490 and the one 

 employed are determined, all mav be located bv simple additions 

 to the readings given. 



