The above can only be considered as a very brief abstract of the system of classification proposed by Dr. Brefield, but it will serve to give some idea of the principle on which the system is based, which is sufficient for our present purpose. Those who wish to study the system in detail will find it treated in a comprehensive manner in Dr. Von Tavel's summary as it appears in the _Vergleichende Morphologie der Pilze_, Jena, 1892. CONIOMYCETES AND HYPHOMYCETES. In the original classification of Fries two of the primary divisions of the sporiferous Fungi were termed, respectively, _Coniomycetes_ and _Hyphomycetes_. This arrangement was accepted by Berkeley, the term _Coniomycetes_ being applied to all fungi in which the naked spores, appearing like an impalpable dust, were the principal feature of the plant, and the term _Hyphomycetes_ to fungi in which the threads or hyphae bearing the spores were the most conspicuous feature. Coniomycetes, as broadly interpreted by Berkeley and other mycologists of his day, included the Uredineae or "rust fungi," the Ustilagines or "smut fungi," the Sphaeropsideae, and the Melanconieae. This arrangement was very unsatisfactory on account of the distinctively different character of the methods of reproduction of the respective groups, and they have since been disassociated and by some authors ranked as distinct orders or families. Others combine Uredinei and Ustilaginei in one group under the name Hypodermei. Familiar examples of Uredinei are seen in the rust of the Barberry leaf, etc., and of the Ustilaginei in the "smut" of corn and the "bunt" of wheat. Some authors combine the Sphaeropsideae with the closely allied Melanconieae. M. C. Cooke contends that the _Sphaeropsideae_ should be considered apart from the _Melanconieae,_ on the fundamental basis that the former possess a distinct perithecium, while the latter do not. The _Sphaeropsideae_ as recently defined by Cooke are "Fungi _possessed of a perithecium, but without asci_, ... sporules or stylospores being produced internally at the apex of more or less distinct supporting hyphae or pedicels, termed sporophores." The Sphaeropsideae somewhat resemble the Pyrenomyceteae in external characteristics, but differ from them in the absence of asci and paraphyses. Saccardo retains all the species in his Sylloge, but relegates them to an inferior position as imperfect fungi. The group _Pyrenomycetes_, or _Sphaeriacei_, as at first recognized by _Fries_, included not only the _Sphaeriacei_ and the _Perisporacei_, but also the _Sphaeropsidei_ and _Melanconiaceae_. Later, when ascigerous fungi were separated from stylosporous fungi, this group was revised, the ascigerous species only being retained. As at present limited, the Pyrenomycetes are "_ascigerous_ fungi having the fructification enclosed within a perithecium."