,'530 BOTANICAL GAZETTE. 



determined by European authorities (he oospores of the two species hardly 

 seemed to present differences sufficiently striking to warrant, on that ground 

 alone, placing them in different sections of the genus. 



23. P. Euphorbise Fuckel. 



P. Euphorbise Fung. Rhenan. no. 40. De Bary 1. c. 114. 

 P. Cypartssix Farlow in Ball. Buss. Inst. II. 236. 

 Exs. Ellis N. A. F. 216. 



Conidiophures repeatedly dichotomous, divisions flexuous, 

 tips widely spreading, spinose, straight or sometimes curved. 

 Conidia globose or ellipsoidal 13-16/;. by 16-19//., pale violet col- 

 ored when mature. Oospores 23-33// in diam., exospore brown, 

 thick, and irregular. 



On Euphorbia rnaculuta. 



Mass. (Farlow), New Jersey (Ellis). Europe. 



Forming rather diffuse patches of a dirty-white color on the under side of 

 the leaves, the upper surface remaining nearly normal. The species is appar- 

 ently not common. I have occasionally seen it ahout Cambridge, but never in 

 quantity except in the unusually wet summer of 1878, when it was common on 

 E. maculata, in the college grounds, in August. I have compared our plant 

 with European specimens of P. Euphorbve, and it seems to me that they specifi- 

 cally agree, although some minor points of difference are present. The conidia 

 of American specimens are certainly violet colored, but, although those of the 

 European form are described as colorless, I have found them to be violet in 

 specimens on E. platyphylla. About the oospores of this species writers do not 

 all agree. They are commonly found with us and have a thick brown exospore 

 with irregular projections. The oosporic [wall is rather rigid and thick, and, 

 if I am not mistaken, has two layers, so that it bears as much resemblance to 

 the oospores of the Parasitical as to those of the Effusce. P. Euphorbia' Fuckel, 

 and P. Oyparissice De Bary, are generally kept distinct, but I must confess that 

 an examination of a good set of both species leads me to think that one is prob- 

 ably a more fully developed form of the other. The form on P. Cyparissias is 

 not known to me in America. 



24. P. grisea Unger. t 



Botrytis grisea Unger Kxanthem. 172. 



/' grisea Unger Bot. Zeit, 1817, 345; De Bary 1. c. 115, PI. XIII. f. 12. 



Conidiophures slender, several times dichotomous. Tips flex- 

 uous, approximate or slightly spreading. Conidia ovate-obtuse, 

 violet colored, 22-30//. by 15-22//.. Oospores large, 30-38//. in. 

 diam., exospore brown. 



On Verrmica alpina. 



Tuckerman's Ravine, Mt. Washington. Europe. 



I have found this species but once, and then at the head of Tuckerman's 

 Ravine, in the month of, September, when oospores as well as conidia were 

 present. ■ Of our Eastern species this attains the highest altitude, reaching to 

 4,500 feet above the sea-level. 



