52 ANGIOCARPOUS LICHENS. 



The spreading base of the perithecium in V. epipolcea, 

 V, subalbicans, and V. rupestris, with the uniseptate hy- 

 ahne sporidia in the former, and the black inner tunic 

 of the second, prevent those plants from being mistaken 

 for V. JDufourii. 



26. V. LINEARIS, nov, sp. Sporidia in asci 8, linear, 



rounded at the extremities, triseptate, pale yellow. 

 Plate XXIII. fig. 1. 



On the same stone with specimens of F. JDufourii, from 

 Cheddar ! in herb. Borrer, 



This little plant which, it is believed, has hitherto been 

 overlooked, will be found represented in the plate of V. 

 Bufouriim E. Bot, Stippl. 2791. It has a thallus similar 

 in structure and colour to that of V. Dufourii ; the 

 apothecia similarly scattered, but very minute, nearly per- 

 fectly hemispherical, somewhat truncate or flattened on 

 the summit, slightly immersed by their bases ; perithe- 

 cium in section thick and clumsy, black, incurved at the 

 base ; nucleus pale, whitish, separated at the base from 

 the stone by a pale tunic. The sporidia are very different 

 in form from any thing I have observed in the other 

 British Verrucariae. 



* * Perithecium neither incurved nor spreading at 

 the base. 



f Inner tunic black. 



27. V. UMBRiNA, Ach, Sporidia in asci 8, oblong, mar- 



gined, pale, Plate XXIII. fig. 2. 



Lichen umbeintjs, Ach. Prod. 14. (1798.) 



Sm. E. Bot. 1499. 



Verrucabia UMBRINA a. Ach. Meth. 122. (1803.) ; L. Univ. 291. 



Fries, L. Ref. 441. 



Verrucaria UMBRINA (in part), Ta^l. Fl. Hib. pt. ii. 93. (1836.) 

 Verrucaria nigrescens (in part). Hook. Br. Fl. ii. 155. (1833.) 



Sussex ! Mr, Borrer. Nent Force, Cumberland ! 

 Mr. W, Bobertson, in herb. Borrer. 



