120 ON THE WHITE RUST OF CABBAGES. 



being intentled to denote the complete absence of perithecium. 

 De Notaris appears, however, to have forgotten that Link liad 

 already proposed a genus Myxosporium, which is in fact synonj'- 

 nious with Nccmaspora, N. crocea being taken as its type to the ex- 

 clusion of the similar Libertella. A third species was published by 

 myself in the Fourth Fasciculus of British Fungi, under the name 

 of Asteroma labes, Asteroma being used with the same latitude 

 in which it had been taken by Fries in his ' Elenchus.' There 

 is no question, however, that it cannot be congeneric with true 

 species of Asteroma^ which undoubtedly possess a real perithe- 

 cium. Subsequently one or two more species were received by 

 Dr. Montague from various quarters, who saw at once that they 

 were congeneric with De Notaris' species on ivy ; but in the 

 absence of specimens, and with the obscurity thrown on Dr. 

 Greville's genus by Unger, he could not be aware of their 

 generic identity with the plant of Greville. For these produc- 

 tions he has proposed the name of Glccosporiicm, and it is but 

 proper courtesy to one who has done so much for these minute 

 and obscure species to adopt his name, unless he should think 

 fit to restore that of Greville, as to the identity of which there is 

 now no doubt in the presejice of abundant opportunities of ex- 

 amining the true structure of his plant. The total absence of 

 perithecium is undoubtedly a most important circumstance, 

 though we must not insist too nicely on the greater or less 

 fusion of the perithecium in some of the lower species of Phoma, 

 Sphseropsis, &c., with the surrounding tissues, as multiplied 

 examinations of the same species under different circumstances 

 show a great difference in this respect, and throw perhaps some 

 doubt upon the stability of Desmazieres' genus Phlyctcene. 

 Indeed, in the genus Discella, where the lower portion of the 

 peritheciiun is often quite confused with the cellular tissue and 

 the stratum from whicli the sporophores are derived, the upper 

 l)ortion of the peritliecium, even in the same species, varies 

 greatly in its degree of development, being sometimes distinctly 

 present, sometimes confused with the cuticle. Another nearly 

 allied genus, if we are not mistaken, is entirely destitute of a 

 perithecium, but unfortunately the fungus which exhibits this 

 character, from the admixture of Sphceria macidcEformis in the 

 plate of Greville {Septoria Ulmi), has been assumed as the 

 type of a genus which clearly possesses a perithecium, and the 

 species now assigned to it are so numerous as to make any retro- 

 grade step extremely inconvenient. The better plan will be to 

 raise Septoria Ulnti to generic importance : tlie name Septorella 

 is sufficiently distinct, and the genus will be characterised by 

 possessing tlie characters of Glceosporium with the addition of 

 tiie existence of true septa in the spores. 



A fresh examination of specimens in my own herbarium and 



