OF ARTS AND SCIENCES. 269 



found on Pyrus arlutlfolia and Cratcegus, is somewhat more common 

 than the comparative rarity of conicum in the same region would 

 lead one to expect. R. pyrata was not observed at all, and macroptis 

 only in a single instance. R. botryapites, however, is exceedingly 

 common, altliough no Cupressus is known to me within eight miles. 

 R. transformans was not observed, but was collected at Greenland 

 about a half-mile from the nearest Cupressus. 



While collecting at Mt. Washington, N. H., during the last week in 

 August of the present year, I observed spermogonia with aecidia just 

 forming on leaves of Pyrus Americana along the path from the Mt. 

 Washington carriage road to a point about half a mile below the snow 

 arch in Tuckerman's Ravine. These developed in a moist chamber 

 sufficiently to show the species to be cornuta. Later in the season 

 Prof. Farlow found the same species of Rcestelia well developed upon 

 the same host at an altitude of 2,500 feet on Mt. Moriah, both these 

 localities being miles from any Juniperus. Prof. Farlow has also col- 

 lected the most typical form of cornuta at Eastport, Maine, on the 

 same host. 



In the vicinity of Boston, the various Gymnosporangia are about 

 equally common, with the exception of the Cupressus forms, and here 

 also hotryapites is far more abundant and widely distributed than the 

 comparative infrequency of Cupressus localities would lead one to 

 expect. 



Despite these discrepancies, the species of Gymnosporangia with 

 their Rcestelice, assuming my determination of lacerata and cornuta to 

 be correct, may be with tolerable safety summarized as follows : — 



G. conicum = R. cornuta. 



G. clavipes = R. aurantiaca. 



G. clavariceforme = R. lacerata. 



G. macropus = R. pyrata. 



G. hiseptatum = R. hotryapites. 



G. Ellisii = R. transformans probably. 



G. glohosum = ?. 



In closing, I must express my great obligation to Prof. Farlow for 

 advice and assistance, as well as for the privilege of examining a large 

 number of exsiccati without which any satisfactory results as regards 

 the more obscure Roestelice would have been impossible. 



