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THELOCARPON INTERMEDIELLUM. Nyl 

 IN BRITAIN. 



By W. Phillips. 



Thelocarpon intermediellum, Nyl. The following arc the cha- 

 racters of this minute lichen, given by Dr. Nylander, in " Flora," 

 18G5, p. 2G0. " Extus simile pr«cedenti (Th. Laurerii, Flot.), 

 sed globuli paullo majores (diam. 0.2 millim.). Thecae myrios- 

 porse, spora3 oblonga? (long 0.0035-0.0050 millim., crass. 0.0020 

 millim). Vulgo medio obsolete tenuiores et ntroque apice obtuse 

 incrassatulae, paraphyses nulla;. Gelatina hymcnea iodo vinose 

 fulvescens, thecal dilute caerulescentes." 



" Ad lignum alni putrescens in Finlandia media (Novvlin)." 



" A Th. Laureii differt magnitudine paullo majore, sporis aliis 

 et defectu paraphysium. Adsunt filamenta ostiolaria brevia gracilia 

 fasciculata in supera parte cavitatis perithecii (omnino sterigmata 

 simulantia spermogonii)." 



To this I would add the following details from our British 

 specimens : — 



Thallus thin, yellowish-green, but evanescent. Apothecia scat- 

 tered, occasionally crowded or adnexed, yellowish-green, small, 

 globoso-depressed and umbilicate, when mature pierced with a 

 minute pore (fig. d.). In a careful section under the microscope, 

 I saw the spores escaping by the pore with a jerking motion. The 

 perithecium is externally crustaceous in texture, and very firm, pre- 

 ferring to divide at the base when crushed, and so allowing the asci 

 to escape downwards. The inner walls of the perithecium are 

 clothed with minute branched threads (fig. g), which I take to be the 

 " filamenta ostiolaria" of Dr. Nylander, but which are not confined 

 to the immediate vicinity of the ostiolum. The asci, when perfect, 

 are large, ventricose, attenuated in the upper part, and also at the 

 base, and have innumerable sporidia (fig. e). They adhere so firmly 

 to the hymenium, that if a group be pressed they spread in a radiate 

 manner from a common centre, when the young asci can be seen in 

 all stages of growth — bluntly clavate, cylindrical, fusiform, and as 

 above described. The sporidia (fig. h), are very minute (0.0035- 

 0.0050 X 0.0020 millim., Nyl.) oblong, hyaline, obtuse at the ends, 

 appearing to have a septum in the middle, but only apparently so. 

 being in reality as described by Nylander, thinner in the middle 

 portion and thickened at the apices. There are no paraphyses, a 

 character which distinguishes this from the other species of the genus. 



I have tried in vain to obtain the blue reaction with iodine in the 

 asci, which Dr. Nylander has observed in this species, ami can 

 offer no reason for my want of success, as I use a solution strictly 

 according with his formula. The only reaction I see is the " vinoso- 

 fulvescent" colour assumed by the asci, as the result of their large 



