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It will he seen tliab tliis curious fungus hitherto unknown in 

 America was first described by Hoffmann, the date of the Icones being 

 18G3, but it was not, however, recognized by him as belonging to the 

 Ust'dagineae, to which it seems to be correctly referred by Corun. If 

 we are to follow the system of nomenclature in vogue on the continent 

 the s):>ecies would be called Doassansia occulta (H. Hofim.) Corun. 

 The genus as characterized by Corun is marked by the fact that the 

 external cells of the sori remain as a sterile covering, while the internal 

 cells on the rupture of the sori give off short germinal tubes, which 

 bear at their tips whorls of short cells as in the genus TiUetia. Tlie 

 germination was seen by Corun in D. Alismatis, a species which has also 

 been found recently in the United States. As I have said, the material 

 first sent by Mr. Fletcher in 1882, was in alcohol, and the germination 

 could not be seen. In 1883, I received some fresh material from Mr. 

 Fletcher, hwt at the time of sending the spores were not mature, appar- 

 ently, and I was unable to make them germinate. If the form on 

 Potaniogeton acts similarly to that on Alisma, it ought to be an easy 

 matter for observers in Canada to discover the mode of germination. 

 According to Corun it is only necessary to place the ripe sori of 

 D. Alismatis in a damp place, when they quickly split open and the 

 internal cells at once give off the characteristic germinal tubes. From 

 the accompanying figure of a germinating spoi-e of I). Alismatis, one can 

 see what to expect from the form on Potamogeton. 



D. occulta has also been found by Mr. Fletcher or P. j^usillus, 

 P, 2}er/oliatus var. lanceolatus, and P. natans in Canada, and its range 

 ■will perhaps be found to extend considerably southward. Besides the 

 true s])ecies of Doassansia, already mentioned, a third form was doubt- 

 fully referred by me to the same genus in a paper in the Botanical 

 Gazette, August, 1883. It forms small black spots in the leaves of 

 Epilobium alpinum in the White Mountains, and may be expected 

 farther north. Any collector so fortunate as to find it, should, if 

 possible, watch the germination. 



