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 Tubercmia, 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 Ev/ropcea. 

 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 Great 

 Britain. The spores are curious, being composed 

 of a number of cells arranged in the form of a 

 hoUow 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, however, it is in no way connected. 



