BOTANICAL GAZETTE. 27 



.1 



found in this country, but a form found on Thaliotrum dioicum 

 in Wisconsin, by Prof. Wm. Trelease, is very nearly related to 

 Ent. Ranunculi, although it would be going too far, at present, 

 to call the two identical. The fungus on Thalictrum produces on 

 the leaves rather small circular spots, which are at first yellow 

 and later black. On the specimens which I have examined the 

 conidia were not in very good condition, and it would be neces- 

 sary to examine more mature specimens before expressing a de- 

 cided opinion on the species. The conidia were in small patches 

 on the under surface of the leaves, and the conidial spores were 

 linear, acute, 11-20 />■ long by about 3 i>- broad. The spores were 

 abundant in the interior of the leaves, but hardly mature, and 

 measured 9 12 // in diameter. 



The most common Entyloma, at least in the east, is one which 

 occurs on Compositce. Several years ago, when looking for the 

 oospores of Peronospora Halstedii on Ambrosia artemisiafolia, I 

 repeatedly found bodies which were evidently not the desired 

 oospores, although the Peronospora was growing on the leaves, 

 but rather the spores of an Entyloma. Since then I have found 

 specimens on Ambrosia with conidia as well as deep-seated spores, 

 and what is evidently the same fungus was found in a luxuriant 

 condition on Aster puniceus at Wood's Holl by Trelease. I have 

 since repeatedly found the fungus on Ambrosia and Aster 

 in small quantities, and it was abundant on Aster puniceus, 

 growing at the top of Tuckerman's ravine on Mt. Washington, 

 in September, 1882. On Ambrosia the fungus causes yellowish 

 or grayish discolorations of indefinite shape, which become 

 eventually black. On Aster the spots are more circumscribed 

 and, although generally yellow, they sometimes have a purple 

 border and the leaves become slightly thickened, which is not the 

 case when it grows on Ambrosia. The conidia form farinaceous 

 spots on the under surface of the leaves, which they sometimes 

 almost cover. The determination of our species is doubtful. 

 Several Entylomata are known on Composite. Ent. Calendula' 

 (Oudemans) and Ent. Picridis, Rostrup, of Europe, are said 

 to be destitute of conidia and, if we accept the statement as 

 absolute, our form must be different. The spores of our Enty- 

 loma average about 7.5-11.5 ,«, while those of Ent. Calendula? 

 are often from 11-15 fi in diameter. Of Ent. Picridis I have 

 examined only the specimen in Myc. Univ. No. 1815, in which 

 the measurements more nearly resemble those of our own species. 

 Of previously described American forms there is a Protomyces 

 polyspora, Peck, in Myc. Univ. No. 1813, on Ambrosia trifida 

 from New York. In my specimen there are no conidia nor are 



