134 LICHENES. 



dered, entirely formed of the substance of the thallus, the disk 

 sometimes coloured. 



/3. Apothecia uniform, not, or scarcely, margined, suborbicular, often 

 having the appearance of the nail of the human hand (peltce). 



Fam. XI. PeltigerejE. 



21. Solorina. Thallus foliaceous, coriaceous, lobed, free, be- 

 neath having fibrous or woolly veins. Apothecia ( peltce) adnate, 

 sometimes immersed, orbicular (distant from the margin), not 

 bordered. 



22. Peltidea. Thallus foliaceous, coriaceous or membran- 

 aceous, spreading, lobed, with woolly veins beneath, the lobules 

 fertile. Apothecia ( peltce) suborbicular, adnate on the tipper 

 side of the lobules or proper portions of the thallus and having 

 a border formed of the thallus. 



23. Nephroma. Thallus foliaceous, coriaceous or membran- 

 aceous, spreading, lobed, naked or hairy beneath, the lobules 

 fertile. Apothecia (peltce) orbicular, reniform, adnate on the 

 underside of the lobules or proper portions of the thallus and 

 having a border formed of the thallus. 



b. Attachment of the, more or less orbicular, thallus by the centre. 



Fam. XII. Umbilicarie^s. 



24. Gvrophora. Thallus foliaceous, coriaceous or membran- 

 aceous, fixed by the centre, peltate. Apothecia (trices or gyromata) 

 orbicular, subscutelliform, sessile and adnate, covered by a black 

 membrane, the disk marked with concentric circles or plicce with 

 a border of its own substance. 



25. Umbilicaria. Thallus foliaceous, coriaceo-membran- 

 aceous, pustuled, fixed by the centre, peltate. Apothecia orbi- 

 cular, somewhat concave, adnate, covered by a black mem- 

 brane, the disk at length tubercled, with a border of its own 

 substance. 



B. Upper and under surfaces of the thallus alike. 



a. Thallus usually compressed and laciniated. Apothecia scutel- 

 liform (scutellce). 



Fam. XIII. Ramaline^:. 



26. Cetraria. Thallus foliaceous, cartilagineo-membraua- 

 ceous, ascending or spreading, lobed and laciniated, on each side 

 smooth and naked. Apothecia orbicular, obliquely adnate with 

 the margin of the thallus, the lower portion being free (not 

 united with the thallus); the disk coloured, plano-concave, with 

 a border formed of the thallus and inflexed. 



