276 PYRKNOCARPKI [VKRRUCARIA 



The order is distinguished by the crustaccoiis thalhis, bright-green 

 gonidia and simple fruits. There are seven British genera : — 



Gonidia not present in hymenium. 

 Paraph yses disappearing. 



Spores simple 105. Verrucaria. 



Spores 1-3-septate 106. Thelidium. 



Spores muriform 107. Polyblastia. 



Paraphyses persistent. 



Spores simple 108. Thrombium. 



Spores multi-septate 109. Gongylia. 



Spores muriform 110. Microglaena. 



Gonidia present in hymenium. 



Spores muriform 111. Staurothele. 



105. VERRUCARIA Pers.in Ust. Ann. Bot. vii. p. 23 (1794) 

 pro parte (non Web. nee Humb.), emend. Th. Fr. Lich. Arct. 

 p. 267 {I860).— Lithocia S. F. Gray Nat. Arr. i. p. 497 (1821) 

 pro parte. (PL 41.) 



Thallus crustaceous, continuous, areolate or pulverulent, some- 

 times developed within the substratum. Algal cells Plenrococcus 

 or Palmella. Perithecia immersed in the thallus or superficial, 

 the outer wall o£ a carbonaceous or horny structure completely 

 surrounding the perithecium (entire) or developed only over the 

 upper part (dimidiate), opening above by a pore or slit (ostiole) ; 

 paraphyses soon becoming mucilaginous and disappearing ; 

 filaments within the ostiole (periphijses) well developed ; asci 

 8-spored ; spores ellipsoid or subglobose, colourless, rarely brown. 



The Verrucaria of early authors was based on characters that 

 belong to widely different Lichens. Persoon first defined the genus as 

 possessing subglobose fruits ; Th. Fries restricted it to those species 

 with simple usually colourless spores and with paraphyses more or 

 less dissolved in mucilage. In some species the dark outer perithecial 

 wall is strongly developed only over the upper half of the fruits and 

 spreads out at the base, a colourless or brownish layer of cells called 

 the inner wall or tunic being continued under the base ; this character 

 is considered by some lichenologists to have generic value — Lithocia 

 S. F. Gray, Lithoicea Massal. Mem. Lich. p. 141 (1853). 



Maritime species growing within reach of waves or spray from the 

 sea ; thallus more or less gelatinous when moist. 



1. V. maura Wahlenb. in Ach. Meth. Suppl. p. 19 (1803).— 

 Thallus black or dark-reddish or brownish-black, thickish, or 

 thin, smooth or subgelatinous, shining or occasionally somewhat 

 scabrid, cracked into minute areolae. Perithecia moderate in 

 size, hemispherical, scattered, immersed in the thallus, the ostiole 

 more or less visible ; perithecial wall dimidiate and spreading at 

 the base, a thin black layer being continued under the base ; 

 spores ellipsoid, 0,012-17 mm. long, 0,007-8 mm. thick, some- 

 times rather larger ; hymenial gelatine wine-red with iodine. — 

 Hook. Fl. Scot. ii. p. 43 & in Sm. Engl. Fl. v. p. 154 ; Grev. Fl. 



