COLLEMA. 149 



On the earth in calcareous soils. Pennsylvania, Mulilenberg 



Catal. 1818. Muhlenberg's plant may very probably have 



been determined by Acharius ; but the species is taken here for 

 a collective one, as by Nylander I: c., and more thoroughly yet 

 by Arnold (Fragm. in Flora, 1867). It is without doubt largely 

 represented in North America, but abounds peculiarly in diffi- 

 culties, which do not appear to be as yet resolvable in Europe ; 

 as certainly not here. With present knowledge, beside what 

 may vaguely be taken for true C. pulposum, the group may be 

 considered as represented with us by the five following, at least 

 sub-species, the claims of which to higher rank are left open. 

 Three of them are received as species by most authors ; the 

 other two are recent determinations. 



12(b). C. Texanum, Tuckerm. ; thallus sub - stellate ; the 

 more or less narrowed, radiant, finally ascendant lobes pal- 

 mately rnultifid, and beset at length with wart-like lobules; 

 apothecia as in 12. Spores ovoid, persistently bilocular, decolo- 

 rate, ^ mic. Suppl. 2, I c. p. 200. 



On dead twigs, etc., in the valley of the Rio Grande, and on 

 calcareous earth in the valley of the Blanco, Texas (Wright), 

 Tuckerman I. c. 1859. On calcareous earth, Alabama, Peters. 



The lobation of the originally described lichen suggests 



that of C. laciniatum, but the earth specimens depart less from 

 C. pulposmn ; and the distinction turns on the spores. 



12(c). C. tenax (Sw.) Ach.; thallus thinnish, the ample lobes 

 expanded and appressed (or now also ascendant and compli- 

 cate) ; lead-coloured or yellowish-green ; apothecia immersed 

 but becoming superficial ; the rufous disk bordered by a thick, 

 from entire becoming rugose-crenulate margin. Spores as in 

 12. Ach. Syn. p. 314. Tuck. Lich. exs. n. 148. 



On the earth in calcareous soils. Pennsylvania (Muhleriberg], 

 Acharius, Syn. 1814. Vermont, Eussell. New York, Sartwell. 



Ohio, Lesquereux. Missouri, Hall. Conspicuous, for the most 



part, as well by the colours, as the sunken fruit ; but the char- 

 acters do not always hold. 



I2(d). C.crispum,~BoTT.', thallus thinnish ; olivaceous-green; 

 lobes of the circumference explanate, those of the centre with 

 raised, dentate -granulate and plicate edges, the whole covered 

 with and concealed by the numerous fruit ; apothecia more or 



