64 THE JOURNAL OF BOTANY 



The septum of the conidia was about ^-^ of the length from 

 the base. 



207. Pestalozzia conigena (Lev.) Sacc. Syll. Fung. iii. 792. 

 Heaps of spores small, black, scattered or gregarious, erumpent, 



surrounded by the lacmiae of the torn epidermis. Conidia fusoid, 

 4-septate, the three middle loculi dark olivaceous, middle one 

 usually darkest, 25-27 X 7 /x; pedicels short, very delicate; aristae 

 2-3, shortish, stiff, pellucid, more or less recurved. (Tab. 516, 

 fig. 12.) 



On cones of Thuja occidentalism Studley Castle, March. On 

 the same cones v^^as Pleospora thujcd m. ; see no. 188. 



208. MucoR PLUMBEUS Bon. Abh. Nat.-forsch. Ges. Halle, 

 viii. 109 (1864). Mucor spinosus Van Tieghem (1876) ; Fischer, 

 Phycom. p. 203 ; Trans. Brit. Myc. Soc. i. 193, pi. 9, fig. 8; Grove, 

 Journ. Econ. Biol. vi. pt. 2, p. 38, pi. iii. figs. 1-9. 



Sporangiophore ^-1 cm. high, branched. Sporangia round, up 

 to 80 /x diam., brownish, at length black. Columella oblong or 

 pear-shaped, provided at the summit with several (1-15) short 

 stumpy or spiny processes. Spores spherical, smooth, 4-6 or even 

 8 /x diam., with a distinct greyish brown tint. 



On various substances, Birmingham. There was mixed with 

 it a variety (var. recurvus m., I. c), in which the branches were 

 curved arcuately downwards. Some observers have found the 

 spores of this species to be rough, not smooth. 



209. Peronospora alsinearum Casp. Fischer, Phycom. p. 452. 

 Conidiophores in dense whitish tufts, 200 /x high, dichotomous 



above ; conidia ellipsoid, varying much in size and form, 26-29 x 

 16-21 ft. Oospores roundish, bright chestnut-brown, marked with 

 a regular net-work of strong ridges. 



On Spergula arvensis and Stellaria media. Oospores were 

 abundant in early autumn, especially in the leaves, in both cases. 



210. Peronospora potentill^ De Bary, Fischer, Phycomyc. 

 p. 473. 



Conidiophores forming small dense clusters here and there, 

 300 X 500 /x high ; stalk slender, 4-5 times dichotomous in the 

 upper one-third. Conidia ellipsoid, pale violet, about 22 x 16 /x. 

 Oospores not seen. 



On the under side of leaves of Potentilla Fragariastriim, 

 Bewdley (Ws.), August, September. Also on Sanguisorha offici- 

 nalis y Water Orton (Wk.). On the former, the conidiophores are 

 mixed with the hairs of the leaf, which are longer than they, and 

 so are not easily to be seen, were it not that the parts of the leaf 

 which they occupy are distinctly visible on the upper side as pallid 

 spots, each exactly delimited by venules. 



211. Peronospora alta Fckl. Fischer, Phycomyc. p. 483. 

 Conidiophores in loose scattered tufts, chiefly on the under 



side, greyish, occupying large patches which show pale yellowish 

 on the upper surface of the leaf, single or two or three together 

 emerging from the stomata, slender, 200-400 /x high ; branches 

 confined to the upper third, 5-6 times forked, erecto-patent, un- 



