280 



Prof. Dr. C. Meresclikovsky's Diagnoses 



Var. detrita, forma albescens^ Mer. 

 Mereschkovsky, I. c. p. 224. 

 Thallo sordide albescente vel griseo-albescente. Ad ssepimenta. 



Spec. orig. (numeros.) ibidem, 

 llossia Media (Kazan). 



Forma mgreseens, Mer. 

 Mereschkovsky, I. c. 



Thallo obscure cinereo-nigrescente vel nigrescente ; apothecia parva, 

 disco nigro, nudo, margine integro. Ad saepinieuta. 



Spec. orig. (unraeros.) ibidem. 

 llossia Media (Kazan). 



In order to make the distinction between the two allied 

 species — Physcia lahrata, Mer., and Physcia virella (Ach.), 

 Mer. — more clear, I give here two figures showing the peri- 

 pheral lobes, and below a longitudinal section along a lobe. 

 The darkened parts represent the sorals, being superficial 

 in Ph. virella and terminal or lateral in Ph. labrata. 



Fig. 1. 



Fig. 2. 



Fig. 1. — Physcia virella (Ach.), Mer. 

 Fig. 2. — Physcia labrata, Mer. 



Physcia ohsctira, forma diapersa, Mer. 



Mereschkovskv, Contrib. fl. lich^nol. d. envir. d. Kazan, Hedwigia, 

 1919, p. 226. 



Thallo cinereo, sicut in forma typica, sa;pe valde extenso, laciniis 

 brevibus, sparsis, rosulas haud formaue, sorediis destitute ; apo- 

 thecia mediocria vel sat parva, disco fusco-uigricante, uudo, 



