OF ARTS AND SCIENCES. 16 



The type of this subgenus is D. AUsmatis, Cornu, which represents 

 Cornu's idea of Doassansia. 



1. D. Epilobii, Farlow. 



On leaves of Epilobium alpinum. 



United States ! 



The cells of the cortex of this species are very small and flattened, 

 and the sori, on this account, very closely resemble those of 

 D. decipiens, Winter. It may perhaps be looked upon as a form 

 intermediate between the group represented by D. decipiens and 

 the group of the Eudoassansice. 



2. D. HottonifB, (Rostr.), De Toni. 

 On leaves of Hottonia palusfris. 

 Denmark !, Germany !, France ! . 



3. D. Sagittarice, (Westend.), Fisch. 



On leaves of Sagittaria sagittifoUa^ graminea, variabUis, and Mon- 

 tevidensh. 



Italy !, France !, Germany !, Belgium !, England ! ; Argentine Re- 

 public ; Canada !, United States ! . 



4. D. opaca, sp. nov. Spot orbicular, slightly swollen on both surfaces 



of the leaf, lemon-yellow, at length dark brown and opaque. Sori 

 crowded, indistinct when viewed with a lens, globular to almost 

 cubical, 200-300 /x by 80-100 /a, light brown. Spores rather 

 loosely compacted together, nearly spherical, 10-15 /x in diameter. 

 Cortical cells of various shapes, from brick-shaped to almost 

 cubical. Germination unknown. 

 On leaves of Sagittaria variabilis. 

 United States ! (Newton, Mass., W. G. Farlow !, Medford, Mass. !, 



Norwich, Conn. !). 

 This species was mentioned by Farlow * under the name of Pro- 

 tomyces Sagittarice, as occurring at Newton, Mass. The same form 

 has been collected by myself, both at Medford, Mass., and at Norwich, 

 Conn., in abundance, and has been studied in all stages of develop- 

 ment. The species differs decidedly from D. Sagittarice in habit 

 and form of the sorus, as well as in the character of the cortical 

 cells. Sowings of the spores have been repeatedly made, but the 

 germination, unfortunately, has not been obtained. The species 

 is readily detected by holding an infected leaf between the eye and 



* Bot. Gaz., Vol. VIII. p. 276, August, 1883. 



