THE PARASITIC EXOASCEAE. 149 



has progressed side by side. He shows that Exoasceae, Hviiig 

 on related hosts, agree so closely in their ascogenous forms, 

 that it is evident they are generically related species. On this 

 ground he sets up a genus containing many species, and names 

 it Taphrina. According to the host-plants, this genus is 

 divided into four stems, and from it twenty-five species are 

 separated off as the genus Magnusidla. Giesenhagen's systematic 

 division, gives a synopsis of the host-plants and their distri- 

 bution as follows : 



I. Genus. Taphrina : asci club-shaped to cylindrical. 



A. Filices-&iQyi\, on Ferns : asci slender, club-shaped; tapering to 

 both ends, rounded apex, greatest breadth in the upper quarter 

 of the ascus. 



T. cor mi cervi (Giesh.) on Asjndivm arista f inn in East 

 Indies and Polynesia. 



T. Jilicina (Rostr.) on Aspidium s2)inulosnvi in Scan- 

 dinavia and ]>alkan-peninsula. 



T. Laurencia (Giesh.) on Ftcris quadriaurita in Ceylon. 



T. fasciculata (Lag. et Sad.) on Ncphrodivm in South 

 America. 



T. lutcsccns (Kostr.) on Aspidicm T/uiijpfrris in Denmark. 



B. Fctula-stein on Jidifforac: asci plump, cylindrical, with 

 rounded apex or even a slight depression there. 



(1) On Ulmaceae : T. ulmi (Johan.) on Uhmis montaua and 



U. campestris in Central Europe and North America. 

 T. cdtis (Sad.) on Celtis australis in North Italy and 

 Switzerland. 



(2) On Bdvlaceac. 

 («) On Betv.la : 



T. alpina (Johan.) on JJ. nana in Scandinavia. 



T. imim (Johan.) on B. nana in Scandinavia. 



T. behUae (Johan.) on B. vernicosa, B. puhcsccns, and IJ. 



turkestanica in Central Europe. 

 T. Ictidina (Eostr.) on B. imhcsccns, and />'. odorotn in 



Germany, Denmark, and Scandinavia. 

 T. carnea (Johan.) on B. odorata, B. imhciiccns, B. nana, 



B. intermedia in Scandinavia, Tyrol, and Silesia. 

 T. bacieriospermmn (Johan.) on B. nana in Scandinavia 



and Greenland. 



