1857.] SCOTTISH BOTANY. 291 



those progenitors which were cultivated and retained within limits 

 which they were intended to adorn, by fair hands now long moul- 

 dering in the tomb ; but this consideration did not detract from 

 the interest they possessed in our eyes, for the situations in 

 which we found them were sufficiently wild, and the contest they 

 maintained with myriads of other autochthonous plants, which 

 strove to obtain exclusive possession of the ground, was certainly 

 worthy of admiration. Of Cryptogamic plants we observed a 

 considerable variety on the trees and walls; but we gathered 

 only one rare Moss, the Neckera pumila, which formed wide, 

 silky patches among the Jungermannia on the trunks of the 

 Beech-trees. I found it in considerable abundance a few months 

 previously in the woods around New Abbey in Kircudbrightshire. 

 It is pretty common about Inverary, though unknown, as far as 

 I am aware, in every other district in Scotland. But the chief 

 rarity of the place, the plant upon the discovery of which we 

 principally congratulated ourselves, was the very curious little 

 Tree-Alga, the Chroolepus Arnottii, very appropriately named 

 after Professor Walker Arnott of Glasgow, who, besides being its 

 first discoverer, is a native of Arlary, in the same county, thus 

 possessing a double title to be called its prototype. We found it 

 in a magnificent avenue of Yews a little above the castle, which, 

 from the slow growth and immense duration of the tree, must 

 have put forth their youthful shoots when the foundation-stone 

 of the old structure was laid, long before Queen Mary- was an 

 unhappy prisoner in the neighbouring castle of Lochleven, and 

 whose thick branches, gnarled by the teeth of centuries, and 

 dusky foliage, created a sepulchral gloom even in the sunniest 

 summer noon. A dark exudation flowed out from the broken 

 and furrowed bark of each tree near the root, which soon har- 

 dened on exposure to the air ; and on this matrix the Chroolepus 

 grows. At an early stage of its development it spreads over the 

 surface of the moist bark, in thin, scattered, flaky patches, which 

 present a close resemblance to the common Mouse-skin Byssus 

 {Racodium cellare), which is so frequent upon old casks and 

 walls in cellars and wine-vaults. In its mature state it is aggre- 

 gated into more or less rounded tufts, composed of a firm, corky 

 substance, exhibiting, like the Sphcerna deusta, concentric layers 

 of growth when broken, and sometimes attaining an inch in thick- 

 ness. It is constantly kept moist by the exudation from the 



