128 COLLEMEI. 



Trenton, N. Y., etc., Tuckerman Gen. Lich. 1872. Structure 



of the thallus of the present species, in its best conditions (as 

 Fellni. Lich. Arct. n. 101) sufficiently agreeing with that of the 

 other species of this section, and. with Pterygium, Nyl., which is 

 not well at home in Collemei ; and the lichen differs in fact in 

 nothing from Lecothecium of Authors but the very indistinct hy- 

 pothallus. Both the colour, and imperfectly denned, or con- 

 fused structure of b may perhaps be attributable to the action 

 of lime : like a, the lichen is inseparable from the Pannariei. 



******* Jane II a. Thallus crustaceous, squamulose-granu- 

 lose, parenchymatous throughout. Hypothallus obsolete. Goni- 

 mous system of gonimia. Apothecia biatorine. Spores muri- 

 form-plurilocular. (Collema aut Leptogium, Auct.) 



24. P. byssina (Kofm..) Tuckerm.; thallus effuse ; of minute, 

 granulose, or now corallinoid, ash-coloured squamules, passing 

 into scurfy granules ; apothecia small to very small, innate-ses- 

 sile; margin depressed; disk reddish-brown. Spores ovoid- 

 ellipsoid, decolorate, ^ mic. Leptogium, ZwacJch Exs. n. 



174. Nyl. Syn. 1, p. 120. Collema, Koerb. Parerg. p. 410. Pan- 

 naria, Tuck. Gen. p. 56. 



On the earth, Illinois (Hall), Tuckerman I. c. 1872. Massa- 

 chusetts, on bank- walls, Willey. 



Fam. 6. COLLEMEI. 



Thallus various, exhibiting the whole range of variation 

 in form of the Tribe, now shrub-like and ascendant ; or 

 filiform and decumbent ; now, and for the most part, folia- 

 ceous ; and now, at length crust-like ; when moist more or 

 less gelatinous (whence the name Jelly-lichens) the hypo- 

 thallus, except in rare cases, obsolete. Gonimous system 

 exclusively of gonimia, which are now clustered in roundish 

 groups, or more commonly linked together in necklace-like 

 chains, nestling in a homogeneous pulp derived from the 

 dissolution of the thickened membranes. 



For a consideration of the relations of this much-disputed 

 Family to the immediately preceding ones, and of the insupera- 



