296 The Scottish Naturalist. 



I — . Sporae 8nae incolores late ellipsoideae, .012-.014 x 

 .ooS-.oi 1 mm. 



In Himalaya (Sikkim), regione alpina, altlt. 10,000 pedum (coll. 

 D rIs G. Watt, No. 7040). 



Dr G. Watt, who is still botanising in the Himalayas, has sent 

 home extensive collections of lichens. The genus Usnea seems 

 to be largely represented there, and in splendid condition. 



Usnea splendens sp. now — Similis U. Thomsoni et aeque robusta; 

 axis centralis mediocris pallidus; fibrillar medullares albae 

 compacts, I — , interiores K fl. dein rubentes caeteroquin 

 non tinctse. Sporae, .012-. 016 X.008-.011 mm. 



Corticola in Himalaya (Tongloo) altit. 10,000 pedum, D re G. 

 Watt lecta (N is 7057 and 7041). 



Usnea dendritica sp. nov. — Similis U. robusta; axis crassus, 

 pallidus; fibrillar medullares compacts albidas, I roseo-viol- 

 aceas, K fl. dein intense rubentes. Sporse, .01 1-.014 x .0075- 

 .01 mm. 



Corticola prope Tongloo, altit. 10,000 pedum (D r G. Watt). 



Usnea arborea sp. nov. — Similis U. Thomsoni sed robustior nec- 

 non ramulis hinc inde nigro - apiculatis ; axis pertenuis, 

 superficie rufescens, fibrillar medullares laxe arachnoideae I 

 intense vinose violaceas dein sordide ferrugineae, K fl. dein 

 rubentes. Sporae 8nae late ellipsoideae, .012-.015 x .008- 

 .011 mm. 



Corticola in Himalaya (Sikkim) altit. 10,000 pedum (D r G. 

 Watt). 



The reaction by Iodine, which affects the medullary fibres 

 throughout their entire extent, as well as the surface of the axis, 

 is instantaneous and intense, and turns ultimately to a dark 

 fuscous colour. This is perhaps the most robust of the collec- 

 tion. In U. subsordida (Strn.), also, the axis is very slender, 

 although pale on the surface, and the medullary fibres loosely 

 arachnoid, which are tinged here and there a vinoso violaceous 

 colour with I. Accordingly U. subsordida may only be a stunted 

 variety of U. arborea. 



There is still another by Dr Watt from the Himalayas, which 

 agrees in general aspect with U. Thomsoni, but the apothecia 

 can scarcely be said to be terminal, inasmuch as there is always 



