276 



POPULAR HISTORY OF LICHENS. 



glabrous, glaucous or straw-coloured, extremities brownish ; 

 at first papillar, then clavate or cylindrical, at length when 

 fertile fastigiate-ramose. Thallus microphylline. Apothecia 

 reddish-brown, mostly symphycarpeous. It is an alpine and 

 subalpine species growing on heaths on some of our High- 

 land mountains, as Ben-mac-dhui ; but it is rare in this 

 country. It most generally occurs in an abnormal state, 

 having short, vesicular, ventricose or gibbous podetia, bear- 

 ing abortive apothecia. This species was formerly made the 

 basis of a separate genus, Pycnothelia. 



Nat. Ord. XII. COLLEMA CEJE. 



Genus I. COLLEMA, HilL 



Gen. Char. Thallus foliaceous or filamentous ; when moist 

 flaccid, turgescent or purpose-gelatinous (from the gluey matter 

 which it contains abundantly) ; when dry membranaceous, coria- 

 ceous or coriaceous-cartilaginous. Apothecium discoid, scutellate 

 or patellseform, sessile, rarely stipitate, brownish. (Name from 

 KoAAa, gluten or gelatine ; in allusion to the property possessed 

 by the thallus of swelling into a gelatinous mass in water. 

 Hence the Collemas are popularly designated the " Gelatinous" 

 or <e Jelly-Lichens.") 



