The summer spores, or pulverulent spores of the first generation, which are analogous to the Uredospores of _Aregma_, are also capable of germination, for, if placed in favourable circumstances, they will develop very long filiform processes, which either remain simple or become more or less branched, but always nearly uniform in their diameter. M. Tulasne states that he has observed this germination many times, though we have been less fortunate. Of the six species of this genus known to occur in Great Britain, the majority may be commonly met with. That very widely-diffused plant, the wood cow-wheat (_Melampyrum pratense_), known well to all amateur botanists for its pertinacity in drying black, and presenting anything but an inviting appearance to claim for it a place in the herbarium—also becomes the matrix for the development of a member of this genus; _i.e._, the cow-wheat rust (_Coleosporium Rhinanthacearum_, Lev.), and which is found on other allied plants, as the little eyebright (_Euphrasia officinalis_), &c. (Plate VIII. fig. 176). In colour and habit it resembles the last-named species, and its free, echinulate spores (Plate VIII. fig. 177) form a pretty object for the microscope. Another equally common species is found inhabiting the leaves of the sow-thistles (_Sonchus arvensis_ and _S. oleraceus_), and in the autumn may generally be found on either of those plants, presenting the appearance delineated in our plate (Plate VIII. fig. 178). The permanent spores resemble in many points those of the first species, as will be seen from the figure from De Bary’s treatise on this subject (Plate VIII. fig. 179). This is certainly one of the most showy of uredinous fungi, and could not be well overlooked. The butter-bur rust (_Coleosporium petasites_, Lev.) and the Campanula rust (_Coleosporium Campanulæ_, Lev.) are found, the former on the leaves of the butter-bur, and the latter on those of the harebell and other _Campanulæ_, less frequently. We have, however, indicated sufficient, since their great similarity in unprofessional eyes will furnish, in one or two species, all that is desirable for the microscopist.