LICHENES. 135 



27. Roccella. Thallus coriaceo-cartilaginous, rounded or 

 plane, branched or laciniated. Apothecia orbicular, adnate 

 with the thallus i the disk coloured, plano-convex, with a border 

 at length thickened and elevated, formed of the thallus and 

 covering a sublentiform black compact pulverulent powder, con- 

 cealed within the substance of the thallus. 



28. Borrlra. Thallus cartilaginous, branched and laciniated, 

 the segments free, generally grooved beneath, the margins fre- 

 quently ciliated. Apothecia orbicular, peltate, formed of the 

 thallus beneath ; the disk coloured and surrounded by the ele- 

 vated and inflexed border formed also of the thallus. 



29. Everxia. Thallus subcrustaceous, branched and lacini- 

 ated, angled or compressed, cottony within, (intus stuppeus). 

 Apothecia orbicular, scutelliform, sessile ; the disk concave, co- 

 loured, with an inflexed border formed of the thallus. 



30. Ramalixa. Thallus cartilaginous, branched and lacini- 

 ated, somewhat shrubby, generally bearing powdery warts, 

 compactly cottony within. Apothecia orbicular, scutelliform, 

 stipitate and peltate, plane, bordered, entirely formed of the 

 substance of the thallus and nearly of the same colour. 



b. Thallus subcijlindrical y filamentous, mostly pendent. 



u. Thallus ivith a central thread. Apothecia scutelliform, without 

 a border, ciliated (orhillai). 



Fam. XI V r . Usmv. 



31. Usnba. Thallus subcrustaceous, rounded, branched, 

 generally pendulous, with a central ///read. Apothecia (orbillai) 

 orbicular, terminal, peltate, entirely formed of the substance of 

 the thallus and nearly <>1* the same colour, the circumference 

 mostly without a border and (generally) ciliated. 



/3. Thallus without a central thread, sour times slightly compri 

 Apothi eia scutelliform, 



T \M. \\\ CoRNH t i. IRIE E. 



:;■_'. A i.i. < i out a. rAoZ/u* cartilaginous, subfiliform, branch* 

 ed, prostrate or pendulous, somewhat fistulose and cottony 

 within. Apothecia orbicular, thick, sea ile, plane orconvex, more 

 or less bordered, entire!) formed of the thallus and of the same 

 colour. 



83, Corn* i lAria. Thallus cartilaginous, branched, within 

 nearly -olid and cottony. Apothecia orbicular, terminal, ob- 

 liquely peltate, entirely formed of the substance <»»' the thallus. 

 at length convex, more or less bordered and often toothed. 



