332 BOTANICAL GAZETTE. 



rner of 1882. It forms rather small, scattered, frost-like spots on the under 

 side of the leaves. The resemblance to P. viticola and P. Halsledii is striking. 

 The present species, however, has conidiophores whose branches are more fully 

 developed than in those species, although the general plan of the ramification 

 is the same. Although the germination of the conidia has not yet been seen, 

 one can not help thinking that they will prove to germinate by zoospores, so 

 great is the resemblance of the conidia and conidiophores to those of our spe- 

 cies of the section Zoosporiparce. In the Journ. Linn. Soc. X., 363, Berkeley 

 and Curtis describe a Peronospora Oubensis found by Charles Wright on some 

 cucurbitaceous plant in Cuba, which, as far as I have been able to ascertain, is 

 not the same as the present species, judging from the description given. The 

 description is as follows: "Candida; floccis sursum furcatis; ramulis ultimis 

 rectis nee uncinatis, sporis metuheformibus vel oblongis obtusis." An exam- 

 ination of the type in the Curtis collection, where it bears the name Botrytis 

 Oubensis B. & C, shows only a minute Ramularia, which throws no light on the 

 subject. Whether correct or not in assuming that P. sicyicola is distinct from 

 P. Gubensis, the discovery of the species in Wisconsin is of economic importance. 

 If it occurs in Sieyos it may be found on cucumbers, melons, and other Cucurbi- 

 iaeece at some future date, and it may eventually prove injurious to garden 

 crops. Like others of our pinnate species it may, sooner or later, spread east- 

 ward, and, following the example of P. viticola, in time extend even to Europe. 

 I have examined cultivated plants of Sieyos in Cambridge, but have been un- 

 able to find the Peronospora. Echinocystis should also be watched, for, from its 

 close relationship to Sieyos, it is not unlikely that the fungus will be found 

 upon it. A more detailed account of P. sicyicola will be given by the discoverer 

 in another place, and it is to be hoped that he will be able to succeed in ob- 

 serving the germination of the conidia, and ascertain whether the resemblance 

 to P. viticola is preserved in this point also. 



28. P. Illinoensis. 



Conidiophores slender, scattered, loosely 2-3 pinnate above, 

 secondary branches usually horizontal, sometimes secund* Tips 

 acute, short, erect, clustered. Conidia globose, or ovate-obtuse, 

 white, 17-20/.. by 15-18//. Oospores? 



The above unsatisfactory diagnosis is given temporarily to designate a curious 

 form found on some leaves of J < Pennsylvania! received from Prof. T. J. 



Burrill. They were collected, I believe, in Southern 111., by Mr. A. B. Seymour. 

 As will be seen from the description this is another of the pinnate forms which are 

 characteristic of this country. A Peronospora Parietarice is mentioned by Rou- 

 meguere in the Revue Mycologique for July, 1883, and distributed in Fungi 

 Gallici no. 2553. It was found on Parietaria diffusa at Chailly, France. 1 have 

 not yet seen a description of the species which is said by Roumeguere to be 

 P. TJrtwv pro parte. From this statement one can only assume that the Illinois 

 form is not P. Parietaria: Roum. for the former is distinctly pinnate, while the 

 latter, if P. Urticce pro parte, must be assumed to be dichotomous. Unfortunately 

 in my copy of Fungi Gallici the specimen no 2553 only shows a Ramularia, and 



