RUSTS. 101 



those of most of the Puccinice tha,n of a Trichobasis. 

 The large, vigorous, and healthy leaves were less 

 affected. Microscopical examination, at first incom- 

 plete, led us to the conclusion that it was a species 

 of Uredo, which had been met with in France 

 (Uredo Hydrocotyles, Mont.) ; but a re- examination, 

 to which we were prompted by Mr. Currey, led to 

 the conclusion that it belonged rather to the pre- 

 sent genus ; but it can scarcely be associated with 

 any species already described, notwithstanding its 

 apparent affinity with the brown rust found on 

 umbelliferous plants, in which the pustules are in- 

 variably developed on the under surface. Under 

 these circumstances, we have called it the Penny- 

 wort rust (Trichobasis Hydrocotyles), whilst stil\ 

 doubtful whether it is not the same fungus as that 

 described by Montagne, with whose description it 

 agrees in everything, except what is implied by 

 the generic name. It should not be forgotten, 

 that the work in which Montagne first described 

 this species was published when the genus Uredo 

 embraced the present genus, which was separated 

 from it by Leveille twelve years later; and it is 

 possible that this species was included in a more 

 recent work by the same author, in error and 

 without re-examination, under the old name. An 

 examination of authentic specimens of Montague's 

 plant has since settled the point; and we know 

 that both fungi are identical. The character- 

 istic difference between the two genera lies in 



