ON POPLAR 349 



solitary and epiphyllous, up to 1 mm. wide, at first covered by 

 the raised epidermis and a layer of hyphae, at length uncovered 

 and surrounded by the same, distributed over the whole leaf- 

 surface ; spores distinctly oblong, 30 — 40 x 13 — 17 ^ ; epispore 

 about 2 /* thick, at the equator thickened up to 5 — -6 fi, covered 

 with rather distant spines except at the summit which is 

 smooth; paraphyses clavate-capitate, 40 — 70 x 14— 18/*, strongly 

 thickened (up to 10 //,) above. 



Teleutos pores. Sori epiphyllous, minute but united in 

 groups and confluent, distributed over nearly the whole leaf, 

 covered by the epidermis, clear translucent-brown, then red- 

 brown, and at length black; spores prismatic, rounded above 

 and less so below, 40 — 50 or more x7 — 10 /*; epispore pale, 

 scarcely 1/* thick, but reaching 2| — 3 /* above where it is 

 faintly coloured and without evident germ-pore. 



Caeomata on Larix europaea; uredo- and teleutospores on 

 Populus balsamifera (ontariensis), P. canadensis, P. nigra, P. 

 pyramidalis (italica), and also on other species, in September 

 and October. Not uncommon. (Fig. 261.) 



The description of the caeomata is after Klebahn. This species is 

 distinguished from M. Allii-populina by the following points : the elon- 

 gated uredospores have a distinct equatorial thickening or rather swelling ; 

 the teleuto-sori are epiphyllous, and the spores are very slightly thickened 

 at the summit. On P. ontariensis I have seen the teleuto-sori so thick 

 and crisp as to remind one of Phyllachora Ulmi on elm-leaves. 



11. Melampsora Tremulae Tul. 



Melampsora Tremulae Tul. Ann. Sci. Nat. ] 854, p. 95. Cooke, Handb. 

 p. 522; Micr. Fung. p. 219. Plowr. Ured. p. 240. Sacc. Syll. 

 vii. 589. 



(1) Melampsora Larici-tremulae Kleb. 



Caeoma Laricis Plowr. Ured. p. 2G2 p.p. 



Melampsora Larici-tremulae Kleb. in Forstlich.-naturwiss. Zeitschr. 

 1897, p. 4G8. Fischer, Ured. Schweiz, p. 498, f. 315. 



jEcidiospores. Caeomata solitary or in little groups, on 

 yellowish spots, minute, scarcely 1 mm. diam., pale-orange or 

 flesh-colour; spores roundish, oval or polygonal, 14 — 17 x 12— 

 16 /*; epispore about 1 /t thick, verruculose. 



