_Ranunculus repens_, especially whenever that plant is met with in very damp situations. We have seldom found the plant in any profusion without its attendant fungus. Footnote 6: Rabenhorst has proposed _Urocystis_ as the name of this genus, on the ground that _Polycystis_ was priorly applied to a genus of Algæ. Another species of these many-celled smuts is not uncommon in gardens, on the sweet violet, attacking the footstalks of the leaves more commonly than the leaves themselves, and swelling and contorting them (Plate IX. fig. 185). In general structure the spores are very similar to those of the last species, save that the cells are smaller, and a larger number are collected together (Plate IX. fig. 186). So far as we have yet examined the spores of this and the preceding species, they appear to consist of separate and distinct vesicles (probably spores), contained within a hyaline sac or outer membrane, and _not_ to be a single spore divided into cells by numerous septa. A species of equal interest (_Polycystis Colchici_, Tul.) is found on the autumnal crocus, or meadow-saffron (_Colchicum autumnale_). The spores approach nearer to those of the last than of the prior species. A fourth species occurs on the leaves of rye (Plate IX. fig. 187), forming elongated parallel blackish lines (_Polycystis parallela_, B. & Br.). It 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 _Tubercinia_, 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 Europæa_. The parasite attacks the leaves about the month of September, forming bullate or blistered patches one-eighth to one-sixth of an inch broad, containing 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 hollow sphere, with one or two apertures communicating 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.