34 Dr. Deakin on new species of Verrucaria and Sagedia. 



V. Leightonii. (Plate I. fig. 3.) 



Thallus crustaceous, very thin, continuous, indeterminate, 

 dark brownish-gray, somewhat powdery-looking on the surface ; 

 apothecia very small, black, hemispherical; pore minute, at 

 length widely umbilicated; perithecium dimidiate, neither spread- 

 ing nor incurved at the base; nucleus pale yellow, in a thin 

 black tunic ; sporidia ovate, two-celled, contracted at the septa, 

 yellowish-brown . 



Thallus very thin, continuous, indeterminate or limited, with 

 a pale margin ; the surface is even, but when seen through a 

 magnifying power is minutely powdery-looking, with dark points; 

 when dry it is a dull dark gray or mouse-colour, becoming darker 

 and of an olive hue when moistened ; beneath the outer coat and 

 generally through the white substratum are scattered green gra- 

 nular bodies. Apothecia at first very small, prominent, hemi- 

 spherical, without any distinct pore ; at length the top becomes 

 flattened, sunk, and has then^ from the margins being elevated, 

 the appearance of a Lecidea ; when moistened it becomes more 

 elevated from the swelling of the nucleus, and is roughish with 

 slightly elevated points. Perithecium dimidiate, thin, covering 

 half the nucleus, neither spreading nor incurved at the base. 

 Nucleus pale yellowish-brown, hyaline when moist, in a thick 

 black tunic. Sporidia in asci eight, ovate-oblong, more or less 

 pointed or obtuse at the extremities, two-celled, and generally 

 slightly contracted at the septa, dark yellowish-brown, the mar- 

 gin and septa darker. 



Hab. Limestone rocks near the sea, Torquay, Devonshire. 



This little plant appears to have been overlooked, or may have 

 been mistaken for a species of Lecidea, which the apothecia in 

 an old state resemble ; but it will be seen from the description 

 and illustration that its structure is that of a true Verrucaria ; 

 and it is named in compliment to the Rev. W. A. Leighton, the 

 author of the ' British Angiocarpous Lichens,^ in which he has 

 pointed out the way to a more accurate knowledge and satisfac- 

 tory investigation of the structure of Lichens and their distinctive 

 specific characters. 



V. ovata. (Plate IL fig. 4.) 



Thallus crustaceous, dark dull olive-green, thin, terminated 

 by a narrow black line cracked into angular areola ; apothecia 

 black, small, scattered, immersed, hemispherical, the apex be- 

 coming naked, depressed ; pore minute ; perithecium dimidiate, 

 thick, incurved at the base ; nucleus black, in a thin black tunic ; 

 sporidia ovate, single-celled, pale yellow, granulated. 



Thallus thin, in irregular-shaped patches, terminated when 

 growing with other species, which is generally the case, in a 



