258 ADDENDA. 



beneath ; when two or more nuclei are clustered, passing over them 

 all, and so including them in one shell ; the interior is soft, of a very- 

 pale brown, enveloping the nucleus on all sides ; this is white, pellucid, 

 swelling when moist, and then exhibiting, if highly magnified, a dotted 

 gelatinons round substance, at whose base is fixed a bundle of cylin- 

 drical, filiform vessels, slightly curved and attenuated at both extre- 

 mities. 



Page 94, after Verrucaria umbrina, insert — 

 The black crust nearly envelopes, but does not pass beneath the 

 nucleus. 



Page 101, before Porina, insert — 



11. Endocarpon macrocarpon. Substratum of the thallus 

 black, subtartareous, thin; scales very minute, scattered or 

 aggregate, subfoliaceous, sublobate or subcrenate, adpressed, 

 coarsely wrinkled, pale dusky olive when dry, light green when 

 wet. Apothecia much larger than the scales, resting on the 

 substratum, their summits porous. 



On Dunkerron mountain; on transition slate, April 1836 t asso- 

 ciated with Collema nigrum and Lecidea aromatica, Hooker ; all 

 three having a blackish substratum to the thallus. Scales less than a 

 of a line in a diameter, affecting the crevices of rocks exposed to the 

 south ; the young smooth and nearly entire, the older coarsely wrinkled ; 

 often crowded around the neck of the apothecia, which thus appear 

 emergent, but these are sometimes found without any contact with the 

 scales ; and so the generic character does not strictly apply. Our 

 plant bears to Endocarpon the same relation as Psora of Hoffman to 

 Lecidea. The apothecia are many times wider than the scales, glob- 

 ular, pierced above ; having a double perithecium, the exterior hard, 

 black, resting on the substratum or surface of the rock ; the interior 



f>ale flesh-coloured, minutely cellular, rather thick ; the nucleus is co- 

 ourless, transparent, containing oblong bodies which are slightly opaque 

 and vary in size and position. 



12. Endocarpon rugosum. Thallus subtartareous, with 

 tumid, waved, aggregate pruinose tvarls, glaucous grey, not 

 altered when wet ; buds in a coarse whitish powder on the 

 summits of the warts. Apothecia minute, few, scattered, ob- 

 long, quite immersed, with dark-brown depressed summits. 



On transition slate, Dunkerron mountain, April 1S3G. Patches often 

 2 or S feet in diameter, dusky glaucous, without a definite border. 

 Central warts sometimes a line in diameter, the others much less ; all 

 crowded, rounded, waved, sprinkled with a glaucous or brown pruina. 

 These protuberances originate from unequal collections of white cor- 

 tical matter, over which the green parenchymatous layer passes, of an 

 equal thickness, and is continued over adjoining warts. The older 

 buds become concolorous with the thallus. The apothecia are few, 

 not observable with the naked eye ; they have no distinct pore on 

 their thickened dark summits ; they are lineari-oblong, immersed, 

 reaching- into the cortical part of the wart ; the tegument not distin- 

 guishable from the nucleus, which is pale-brownish, smipellucid, gela- 

 tinous when wet. The tvarts of the thallus assume so much the ap- 



