292 SCOTTISH BOTANY. {December, 



tree ; and Professor Arnott is of opinion that its stratified struc- 

 ture internally is owing to the inspissation, at the close of each 

 season^ of this sap^ which it so freely absorbs. When examined 

 under the microscope it presents a beautiful appearance, consist- 

 ing of a heap of little purple-brown beaded necklaces, which are 

 slightly branched and exceedingly fragile. The articulations of 

 these beaded filaments are very nearly as broad as they are long, 

 and are marked by contracted joints, which give them a some- 

 Avhat spherical shape. From its external appearance, place of 

 growth, and microscopic structure, this plant seems to have a 

 closer affinity to the Fungi than to the AlgcE ; and I am strongly 

 inclined to think that it would occupy its proper and natural po- 

 sition if placed among the former in the genus Monilia or Torula. 

 It certainly differs widely in almost every respect from the typical 

 species in the subdivision Helenisporium of Chroolepus. I have 

 frequently observed a somewhat similar production on the trunks 

 of Fir and Larch trees in the Highlands, forming small, black, 

 flocculose patches on the bark, the filaments of which exhibited 

 under the microscope a moniliform structure. Although placed 

 by Klotzsch in the genus Racodium, under the name of R. pino- 

 phila, it has as true a claim, I think, as the plant under conside- 

 ration to be considered a species of Chroolepus. 



I may remark here that a nondescript production occurs very 

 frequently on the knots of Pine-trees, and on the trunks in places 

 where the branches had been broken off", spreading in a continu- 

 ous black powdery patch over the resinous exudation that has 

 oozed out and hardened by exposure to the air. Suspecting it to 

 be a Lichen from the presence of black apothecia-like shields on 

 some species I had gathered, I sent it to my friend the Rev. Mr. 

 Leighton, the author of the ' Angiocarpous Lichens,^ who exa- 

 mined the fructification microscopically, and informed me that it 

 was destitute of asci and contained only a mass of granules or 

 naked sporules. Since then I have satisfied myself that it is the 

 Lichen atratus of Hedwig, or the Patellaria atrata of Fries. It 

 might easily be confounded at first sight with the Chroolepus 

 Arnottii, but the characters I have indicated will sufficiently dis- 

 tinguish it. After we had obtained a sufficient supply of speci- 

 mens of this very interesting plant, which I believe has been 

 found nowhere else in Britain, although I should think it might 

 occur on Yew-trees in other localities, were a careful search in- 

 stituted. 



