The Scottish Naturalist. 



3i 



I botanised chiefly in the parish of Birsay in the north-west 

 corner of the Mainland, near Stromness, near the Stones of Sten- 

 nis, around the village of Finstown, near the head of the Bay of 

 Firth, and in the parish of Orphir, on the south-east of the Main- 

 land. 



In all these localities I found species of Peronosporecs, but 

 mostly in Birsay, and near Finstown. Of Phytophthora i?ifestans y 

 the only species previously recorded,-by myself, from Orkney, I for- 

 tunately saw scarcely a trace this year ; but a fair number of other 

 species were found, including three new to Scotland. They were 

 as follows : 



Cystopus candidus (Pers.) Lev., on inflorescence of Raphanus 

 Raphanistrum, in the parish ot Harray. 



Phytophthora infestans (Mont.), on all parts of Solatium 

 tuberosum, scarce this year, but too often rather plentiful. 



Peronospora (Plasmopara) nivea (Unger), near Finstown, 

 common, on ALgopodium Podagraria, Anthriscus sylvestris y 

 and Angelica sylvestris. 



P. calotheca De Bary, on Galium Aparine in the ruins of the 

 Palace of Birsay. 



P. Viciaa (Berk.) De Bary, on Vicia sepium, rare, between Har- 

 ray and Birsay. 



P. Alsinearum Caspary, on Cerastium triviale, common at 

 Finstown. 



P. parasitica (Pers.) Tul., on Hesperis matronalis, occasionally 

 near Finstown. 



P. Ficarias Tul., on leaves of Ranunculus repens, not scarce in 

 Birsay. 



P. affinis Rossm., on Fumaria officinalis, in a field in Birsay. 

 P. Violae De Bary, on Viola tricolor, scarce, near Finstown and 



Stennis, new to Scotland (found by me in September near 



Ellon, in Aberdeenshire, on var. arvensis). 



Chiefly on the lower surface of the leaves near the base of the stem> 

 effused in a pale greyish-violet coat of clusters of conidiophores, each 

 bifurcated from 5 to 7 times, spreading, branchlets nearly straight, 

 tapering ; conidia ovate or elliptical, membrane nearly hyaline, pale 

 violet, 18-21 by 15 p. 



P. obovata (Bon.), on Spergula arvensis, rare, in a field near 

 Finstown. 



P. Radii De Bary, on Chrysanthemum segetum, common in 



