22 Illinois State Laboratory of Natural History. 



tennis). Thallus at first radiately divided from the centre, 

 which often soon decays; the divisions bifid or di-trichotomous, 

 plane, depressed or canaliculate above, and usually convex and 

 naked or squamulose beneath; margins either naked or spinu- 

 lose-ciliate. Epidermis usually distinct, eporose; air cavities 

 evident in some species, wanting in others. Rootlets papillose 

 within (except in R. Frostii). Named for Ricci, an Italian 

 botanist. 



1. LICHENODES Bisch. Thallus solid, without air cavi- 

 ties; fruit mostly protuberant above; spores about 0.084 mm. in 

 diameter, angular, issuing through openings which at length ap- 

 pear in the upper surface of the thallus. Terrestrial species 

 growing on damp, usually trodden or cultivated ground, and 

 closely adhering to it. 



* Thallus naked on the margins or underneath (without cilia or 



scales). 



1. R. Frostii Aust. Thallus orbicular, 1.3 2.5 cm. in 

 diameter, subsolid, thinnish, subpalmately or radiately divided, 

 cinereous-green, fibrously reticulate, minutely pitted and either 

 plane or channeled above, concolorous or tinged with purple 

 toward the apex beneath, very narrowly membranous, somewhat 

 papillose-squamulose, and often tinged with purple on the mar- 

 gin; divisions linear or subspatulate-linear, subdichotomous; 

 lobes subtruncate and indistinctly emarginate; rootlets smooth 

 or obsoletely papillose within; capsules irregularly disposed, 

 very prominent underneath; spores nearly round, barely 0.051 

 mm. in diameter, fuscous, somewhat margined, minutely and 

 obscurely reticulated and granulose-papillose, the sides strongly 

 depressed when dry. 



Hob. Nev. (Watson], Col. (Wolfe), O. (Beardslee), 111. (Hall). 

 m-Torrey BulL VI, p. 17. 



2. R. Watsoni Aust. Dioecious; thallus of male plant 

 small, fuscous-purple both sides, orbicular, deeply and many 

 times divided, thick, fleshy, broadly pitted, papillose, fibrous- 

 reticulate and icith rather large, terete subclavate, gland-like 

 papilla? (ostioles?) above, densely radiculose and nodulose be- 



