.1911-1912.] Notes on Parasitic A scomycetes. — //. 437 



it, like the divisions between the bricks in a wall. C. Idburni 

 (Pers.) De Not, common on dead branches of laburnum, is 

 said to attack living branches that have been injured by frost 

 or insects ; while C. picece Borthwick has occurred on living 

 buds of Ficea pungens, which, it enveloped with a black crust- 

 like stroma. 



Gibhera vaccinii (Sow,) Fr. grows on living stems of 

 cowberry (Vaccinium Vitis-Idcea). The perithecia, which are 

 black and crowded in clusters, are at first hairy, but after- 

 wards become naked. The asci contain eight nearly colour- 

 less, elliptical, uniseptate spores. 



Gnomoniella and Gnomonia are both remarkable for having 

 the mouth of the perithecium extended into an elongated 

 beak. The spores of Gnomoniella are simple, while those of 

 Gnomonia are divided into two cells by a cross septum. 

 Gnomoniella is represented by two parasitic species which 

 occur on leaves of hazel and hornbeam respectively. G. coryli 

 (Batsch) Sacc. produces, on the under surface of the hazel-leaf, 

 convex black shining stromata, each resembling a little patch 

 of pitch. The perithecia are arranged in a circle, immersed 

 in the stroma, with their elongated necks projecting therefrom. 

 Each ascus contains eight hyaline spores of an oval shape. 

 Similar black stromata are produced by G. fimbriata (Pers.) 

 Sacc. on leaves of hornbeam. Gnomonia is well illustrated by 

 the long-beaked saprophytic fungi so abundant almost every- 

 where in late autumn and winter on fallen leaves and petioles 

 of sycamore, but no common parasitic species calls for our 

 notice here. 



The three remaining genera — Venturia, Stigmatea, and 

 Sphcerella — contain several parasitic leaf-fungi, mostly of very 

 minute size. They all agree in having their hyaline or pale- 

 yellowish spores divided into two cells by a cross septum. 



Venturia is distinguished by the black setse or bristles 

 which occur on the perithecia, especially towards their apical 

 portion. The most common species is V, alchemillce (Grev.) 

 B. & Br., which grows on leaves of lady's -mantle. The 

 perithecia are generally seated on a somewhat pale spot, and 

 arranged in rows or lines radiating outwards from a centre. 

 Of less frequent occurrence are V. glomerata Cke., forming 

 dark clusters on leaves of dove's-foot and other cranesbills ; 



