12 ON A MINUTE NOSTOC WITH SPORES. 



these being always placed singly between two heterocysts. The 

 pairs of heterocysts with the intervening spore occurred at just 

 about the same intervals as in ordinary examples occur the isolated 

 heterocysts; the spores large, broadly elliptic, about one-third 

 longer than broad ; their diameter more than twice the diameter of 

 the heterocysts, about thrice the diameter of the ordinary cells ; 

 the " bright points " of the heterocysts not very conspicuous. 



I would explicitly deprecate any supposition that the observation 

 was founded on any mere isolated filament, met with in the same 

 material as the rest of the ordinary examples of this Nostoc around, 

 and assumed by me to have emanated from some of them, and, 

 therefore, possibly that of some other genus. 



The filaments were not isolated, but contorted about in quite the 

 ordinary way, were still involved in the parent matrix, which was 

 bounded by the distinct pellicle, or " periderm," generically charac- 

 teristic, and in all respects, save the remarkable speciality described, 

 this example was absolutely the same as the others in the same 

 gathering ; in fact, the little Nostoc was intact. It might be said, 

 possibly, this little plant was rather a Monormia, but the definite 

 periderm to the rounded fronds places a bar to the assumption, and 

 I do not think any observer would see it and pronounce it other 

 than a Nostoc. 



In making a drawing for illustration it is of course unnecessary 

 to present more than one spore, with its adjacent heterocysts and 

 a few cells of the filament. To give the total frond and its long, 

 tortuously looped and curved filaments, with their numerous spores 

 and heterocysts, and to convey an idea of the matrix, with the 

 bounding periderm, would have been an unnecessary labour and 

 expense, and to carry it out on the scale of some 400 diameters 

 would have occupied a very considerable space. 



The interest which attaches to this example of a spore-bearing 

 Nostoc will be more apparent after reading my observations on 

 Reess' views, which will follow, and which are necessarily excluded 

 here on account of the limited space at my disposal. 



Australian Fungi. — Mycologists will be glad to learn that the 

 last number of " The Journal of the Linnean Society" (No. 67, for 

 May), contains a valuable communication by the Rev. M. J. Berkeley, 

 on Australian Fungi. In addition, we may observe that the same 

 number contains a communication by Dr. Dickie on the Marine Algee 

 of the Island of Saint Helena, and two communications by Dr. S. (J. 

 Lindberg on Mesotus (Mitten) and Zoopsis (Hook and Thorn.). 



