148 GEOLOGY OF LA SALLE COUNTY. 



VERRUCARIEI. 



In the following' o-enera we approach the limits 

 markino' the close relations of the lower lichens with 

 the funo-i. The absence or slig-ht indications of a 

 thallus have caused Ivichenolog-ists to doubt whether 

 certain species of Verrucaria and Pyrenula should be 

 classed under these names or as Sphaerias. 

 VERRUCARIA, Pers., Tuckerm. Thallus crusta- 

 ceous, sub-tartareous, mostly uniform, apothe- 

 cia g-lobular, black, immersed or prominent, 

 perithecium black. 

 V. pyrenophora, Ach. Nyl. Thallus tartareous, 

 cliinky, ash-colored or continuous and rug-ulose, 

 apothecia prominent, black, laroe conoidal, ses- 

 sile, perithecium dimidiate. Spores 8, colorless. 

 Ach. L. U 285. (1810.) On rocks alono- the 

 Vermillion. 



V. nigrescens, Pers. Thallus nearly black, crus- 

 taceous, uneven, crumbling', and often raised 

 around the apothecia, apothecia black, perithe- 

 cium dimidiate. Spores 8, colorless. On lime- 

 stone along* streams in various localities. 



V. fuscella, Pr. Thallus crustaceous, dark brown, 

 areolate-difPract, black-limitate, smooth, apo- 

 thecia minute, immersed in the areolae. Spores 

 8, colorless. Ach. L. U. 289. Found on calca- 

 reous rocks, Deer Park, as far as observed. A 

 well defined and interesting- species. 



V. muralis, Ach. Thallus whitish, tartareous, 

 mealy or wanting*, apothecia black, semi-im- 

 mersed, hemispherical, perithecium dimidiate. 

 Found on limestone near La Salle, also elsewhere. 



V. viriclula, Ach. Thallus g-reenish olive, are- 



