In their early history the Myxomycetes, or "slime moulds," were classed with the gasteromycetal fungi, and by Fries grouped as a sub-order of the Gasteromycetes, under the name Myxogasters. From this connection they were severed in 1833 by Link, who, recognizing certain distinctive features which entitled them to consideration as an entirely separate group, ranked the Myxogasters, as a separate order, under the title _Myxomycetes_, _Slime moulds_. De Bary, in a monograph on the subject written some years later, questioned the right of this group to the place assigned it in the vegetable world, claiming that the Myxogasters were as nearly related to the animal as to the vegetable kingdom, and changing the name to Mycetozoa. Massee assailed this position in his "Monograph of the Myxogasters," pointing out that De Bary derived his reasons and deductions from the early or vegetative stage of the fungi, without taking sufficiently into account the characteristics of the later or reproductive stage in which the great disparity between these organisms and those of the lower animals becomes apparent. Dr. Rostafinski, the Polish botanist, and pupil of De Bary, adopts the name given the group by De Bary, but applies it in a more restricted sense, classifying on a botanical basis. Both De Bary and Massee have their earnest disciples. M. C. Cooke takes the ground that the Myxomycetes are entitled to mention as "_fungi_ which produce their fructification enclosed within a peridium," although considering them as an aberrant group which, on account of certain peculiarities of their early or vegetative stage, should no longer be classed as having affinity with Gasteromycetes. Without further discussion of the subject, it is sufficient, for our present purpose, to state that mycologists now very generally agree in regarding this group as quite distinct from the Gasteromycetes. The species are minute, rarely exceeding a millimeter in diameter, at first pulpy, then dry. In the early or vegetative stage the "slime mould" is plasmoidal, consisting of a mass of protoplasm without cell wall, and prefers damp surfaces, such as rotting leaves, moist logs, etc. The whole substance is slippery or slimy and presents different hues, red, orange, violet, brown, etc., according to species, but never green. It is in the reproductive or fruiting stage that their resemblance to microscopic puff-balls appears, the sporangium in many species exhibiting a distinct peridium or outer coat which encloses the spores together with the hair-like threads called the capillitium. On the ripening of the spores this peridium ruptures, allowing their escape, the capillitium lending valuable aid in their dissemination. GENERA OF GASTEROMYCETES, ACCORDING TO SACCARDO. I.--PHALLACEAE, OR PHALLOIDEAE.