COMPLEX SMUTS. 93 



has also been found on the leaves of some grasses^ 

 but does not appear to be very common. 



Many similar features are possessed by the two 

 members of a genus named Tithercinia, which have 

 been found in this country. One of the species 

 is parasitic upon a plant which we who inhabit 

 southern England never meet with^ but which is 

 not uncommon in Scotland_, i, e,, Trientalis JEuropcea, 

 The parasite attacks the leaves about the month of 

 September^ forming bullate or blistered patches 

 one-eighth to one-sixth of an inch broad^ contain- 

 ing a mass of black spores (plate III. fig. 52). 

 These spores are irregularly globose^ large^ and 

 opaque,, consisting of a number of distinct cells 

 (plate III. fig. 53). Never having seen other than 

 dried specimens — kindly communicated by Dr. 

 Dickie of Aberdeen^ the discoverer of this species — 

 we cannot add much to its history beyond the 

 published description by the Rev. M. J. Berkeley. 



The other species occurs on potatoes^ and is, 

 during some seasons, common in all parts of Grreat 

 Britain. The spores are curious, being composed 

 of a number of cells arranged in the form of a 

 hollow sphere, with one or two apertures communi- 

 cating with the interior (plate III. fig. 54). They 

 are generally attached by a delicate thread. This 

 species, sometimes confounded with the potato 

 scab, was first described, by Mr. Berkeley, about 

 the time of the appearance of the ^^potato disease,^^ 

 with which, hovfever, it is in no way connected. 



