( 27 ) 

 ORIGINAL COMMUNICATIONS. 



Monograph of the Genus Abrothallus (De Notaris and 

 Tulasne emend.) By W. Lauder Lindsay^ M.D., Perth. 



(Read before Section D. of tlie Meeting of the British Association, 

 at Cheltenham, in August, ]856.) 



The genus Abrothallus, and especially the species here- 

 after described as A. Smithii, have long been familiar to 

 lichenologists under a variety of designations ; but their true 

 structure and place in classification were quite misunderstood 

 until the comparatively recent researches of De Notaris,"^ in 

 Italy, and Tulasne,t in France. A. oxysporus {infra de- 

 script.) has generally been regarded as a species of Endocarpon, 

 especially when it bore only young apothecia; while the 

 apothecia of A. Smithii have been denominated cephalodia, 

 and have been variously looked upon as the abortive, mon- 

 strous, or accessory apothecia of certain Parmelias, Lecideas, 

 and other lichens, or as parasitic fungi. Sir William Hooker, 

 in his 'British Flora,' vol. ii, p. 200 (1833), says that Par- 

 melia saxatilis, and its variety omphalodes, " are liable to be 

 infested with a parasite, which has been called Endocarpon 

 parasiticum, Ach." {' E. Bot.,' 1. 1866.) On furfuraceous states 

 of P. saxatilis the Abrothalli are most abundant. In his 

 'Flora Scotica' (part ii, p. 44, 1821), Hooker gives as the 

 characters of this Endocarpon parasiticum {Lichen parasiticus, 

 'E. Bot.,' t. 1866) : " Th alius coriaceous, convex, rounded, 

 lobed, copper- colom'cd, at length rugged, black and shaggy 

 beneath, orifices scattered, sunk, minute, coal-black, at length 

 convex." This description, in so far as it applies to the apo- 

 thecia, appears to confound the two species A. Smithii and 

 A. oxysporus ; and, in so far as it describes a thallus, it is 

 erroneous, since recent researches have proved the genus 

 Abrothallus to be really athalline. The latter error, how- 

 ever, is rectified in the 'British Flora,' p. 159, where it is 

 stated that the "Endocarpon parasiticum, Ach., is now univer- 

 sally considered to be a portion of the thallus of Parmelia 

 saxatilis or omphalodes deformed by a parasite." The view 



* ' Mem. della reale Accad. delle Sc. di Torino.,' ser. 2, vol. x, p. 351 

 (184.9); and in 'Giorii. bot. Ital.,' aun. ii, fasc. iii-iv, part i, p. 193, 

 (1846). 



f " Meinoire pour servir a THistoire organograpliique et physiologique 

 des Lichens," in the 'Auiiales de.s Sciences NatiircUes,' ser. 3, Botanique, 

 vol. xvii (1853), p. 113. 



VOL. v. E 



