18 THiRSK NATURAL HISTORY SOCIETY. [January, 



to it; though there are a few substances of this class which 

 are attached to and flourish on living vegetation/' He then 

 refers to the agents which effect the decomposition of the leaves 

 of the Laurel {Prunus Lauro-Cerasus) , the Elm^ the Sycamore, 

 and the Beech. The first appears in the form of a small black 

 speckj and when ripe, discharges a yellow powder from the 

 centre. This is named by Lamarck, the two-fronted Uredo 

 [Uredo bifrons). The dark-coloured blotches on the elm-leaf 

 he calls " the plague-spot of its destruction," and this Lamarck 

 nam«s Spharia xylomoides. The dark-coloured spots on the 

 Sycamore {Acer Pseudo-Ptatanus) he calls Xyloma acerinum, 

 which appear in autumn. 



" These specimens," observes the author, " are only individuals 

 among hundreds, which present us with a world of beauty, va- 

 riety, and wonder." 



I would recommend this interesting work for perusal, and I 

 wish some of our other Naturalists would publish their journals. 



I hope some of your readers will favour me with the name 

 of the spots on the leaves of the Viburnum Opulus. I enclose 

 a leaf for your inspection. 



Note. — The spots on the leaves enclosed appear to discharge 

 a yellow powder. 



THIESK NATUEAL HISTOEY SOCIETY. 

 Botanical Exchange Club. 



The monthly meeting of the Thirsk Natural History Society 

 was held on the evening of Friday, the 3rd of December. Miss 

 Warren, of Flushing, near Falmouth, and Mr. Isaac Williamson, 

 Lower Hillgate, Stockport, were admitted as members of the 

 Botanical Exchange Club. 



Mr. J. G. Baker announced the receipt of parcels from Misses 

 Gifford and Warren, Mr. Samuel King, and the Rev. W. M. 

 Hind; and that Mr. A. Irvine had kindly undertaken, for the 

 convenience of the southern members of the Club, to take charge 

 of whatever packets might be forwarded to his residence, and 

 would se^id them in one cover to Thirsk, at the end of the year. 

 He exhibited specimens and communicated notices as under : — 



" North-east Yorkshire. — Fumaria Vaillantii, Lois. — Found by 



