J.INDSAY, ON ABROTHALLUS. 35 



generally associated with A. oxysporus. In a large propor- 

 tion of cases, varieties a and /(3 occurred on the same 

 specimen. Sometimes, however, var. o predominated or was 

 foimd alone, — for example, on dry exposed walls in Highland 

 districts, or on boidders on Highland mountains. At other 

 times, var. /3 was the more abundant form, chiefly on damp 

 and shady roadside walls, both in Lowland and Highland 

 localities. The var. h, in which, according to Tulasne, the 

 spores are all small and pale, I have not met with. 



A. On walls : in Highland districts, built chiefly of granite, 

 gneiss, mica slate, and other primitive or metamorphic rocks ; 

 in Lowland districts, built chiefly of basalt, greenstone, por- 

 phyry, amygdaloid, or other members of the trap series, of 

 new or old red sandstone, &c. 



1 . Craigie Hill, Perth ; with pycnides. Trap, primitive 



and metamorphic rocks. 



2. Birnam Hill, Dunkeld ; with pycnides. Clay slate 



series, including hornblende and chlorite slates. 



3. Craig-y-Barns, Dunkeld; with pycnides. Mica slate 



series. 



4. Amulree road, Strathbraan, Dunkeld; with pycnides. 



Clay slate and mica slate. 



5. Highland road between BlairgowTie and Percy; with 



pycnides. Gneiss. 



6. Highland road between Percy and Spittal of Glenshee; 



with pycnides. Gneiss and quartz rock. 



7. Glenshee, Glen Beg, and Glen Clunie, between Spittal 



of Glenshee and Braemar; pycnides more abundant 

 than in any other station. Mica, hornblende, and 

 chlorite slates ; gneiss and quartz rock. 



8. Eoad between Braemar and Corramulzie Linn ; with 



pycnides. Gneiss. 



9. Glen-tilt road, about Linn of Dee; with pycnides. 



Quartzose mica slate, and gneiss. 



10. Deeside road, near Invercauld, Braemar. Gneiss. 



11. Ben Lawers, Loch Tay; with pycnides. Mica slate. 



12. Banks of Crinan Canal. Gneiss, mica and clay 



slates. 



13. Road between Sligachan and Portree, Isle of Skye; 

 with pycnides. Syenite, greenstone, compact felspar, 

 amygdaloid and other trap rocks. 



14. Great northern road, Uig, Skye; with pycnides. 

 Trap rocks, chiefly amygdaloids, basalts, and green- 

 stones. 



