AFFINITIES OF PELLICULAKIA. 135 



cetes or moulds. In habit, and external appearance, it strongly 

 reminds one of the white mould which precedes many species of 

 Erysiphe, such as the one so common on peas in the autumn, or 

 that which precedes JJncinula on the leaves of the maple. Even 

 under the microscope, there seems to be some kind of relationship ; 

 the interwoven, septate, colourless branched threads are present, 

 but there is an addition of a somewhat gelatinous medium which 

 binds the threads together into a pellicle. The spores and their 

 mode of production is different, and this, in the Hyphomycetes, is a 

 most important distinction. In Oidium the spores are produced in 

 chains, in the present species singly. It is very true that the struc- 

 ture, as seen in a drawing, resembles closely that of some species 

 of Zygodesmus, but there is a peculiarity in the threads of many of 

 the species in that genus that the threads are cut, as it were, nearly 

 through at short distances, or abruptly bent, of which there is not 

 the slightest indication here. The spores are very similar in size 

 and form, but there are two or three features, which appear to us 

 conclusive for rejecting the coffee rot from this genus. In all the 

 species of Zygodesmus the threads are free from any investing 

 medium, the spores are pulverulent, and, moreover, the threads are 

 more or less coloured. Further than this, all the species occur on 

 dead wood or leaves, and in no instance is a species parasitic on 

 living leaves. Although too much reliance is not to be placed on 

 this fact, it is nevertheless noteworthy that genera in which species 

 are parasitic on living plants, there is seldom an exception to this 

 rule, and so in genera which contain species found on dead sub- 

 stances, parasitic species are not found. In illustration of the 

 former, we may cite Peronospora, Ramularia, and Erysiplie ; and 

 of the latter, Dactylium, Sporotrichum, and Zygodesmus. 



The presence of the gelatinous element which binds together the 

 threads and spores into a thin pellicle, which is easily separable 

 from the matrix when moist, is an important feature in determin- 

 ing the affinities of the " Coffee Eot." In the genus Amphihlis- 

 ti-um of Corda, there is said to be such a gelatinous medium. In 

 many species of Fusisporium there is something of the same kind. 

 In Alytosporium, as constituted by Link, and in some other genera, 

 allied to Sp)orotrichwn. Still from all these, there are such mani- 

 fest points of divergence, that no one would venture to associate 

 the present species with any of them. Hence no other course 

 appeared to be open to us but to constitute rellicularia Koleroga 

 the type of a new genus allied to those just alluded to, but distin- 

 guished therefrom by its parasitic habit, sessile, echinulate, globose 

 spores, and the freedom with which it separates from the matrix. 

 Whether or not mycologists will accept this as a sufficient distinc- 

 tion, the present' course has not been adopted without much con- 

 sideration. 



