370 A. Barclay — List of the Uredineae occurring [No. 3, 



Trin. The uredospores on this last mentioned host measure, when just 

 wetted, 21*6 x 20*2 fi. The teleutospores (pnccinia) on the same mea- 

 sure 36 jj. in length by 16 ft at the septum. The septum divides the 

 spore into two equal halves. The promycelia from each cell divide at 

 their ends into four cells, each of which produces a sporidium at the 

 end of a slender sterigma. The sporidia measure from 10 x 6 ft to 

 12 X 7 ft. 



14. — Gymnosporangium clavarij:forme, Jacq. ? 



Pyrns variolosa, Wall. 



An ^cidium (Roestelia) on this single species of the several mem- 

 bers of the PomaceaB in and about Simla is fairly common from May to 

 August : but I have observed in this case, as in several others, that in 

 some years it is more common than in others. For example, in 1885, I 

 found no difficulty in obtaining as many specimens as I desired : in 

 1886, I experienced the greatest difficulty in finding a very few, while 

 now, in 1887, it is again fairly common, though not so common as in 

 1885. It attacks only the leaf-blades and no other parts, so far as my 

 observations have extended, forming well defined patches, orange-red 

 above and yellowish below, the upper surface being densely studded 

 with spermogonia. Generally the fully developed older dark green 

 leaves bear these secidial patches, the younger paler leaves being only 

 exceptionally attacked and these late in the season, namely, in July, 

 The area of the leaf blade invaded varies in extent from a few milli- 

 meters in diameter to 1 c. m. or even a little more, and is considerably 

 thickened. While the thickness of the normal leaf blade is about 0*170 

 to 0190 m.m., the attacked parts when eecidia are developed measure 

 about 0'880 m.m. The thickening of the leaf blade is due mostly to an 

 apparent proliferation of the spongy tissue cells, which are also altered 

 in form, becoming long palisade-like cells instead of irregularly round 

 as under normal conditions. The true normal palisade-cells are about 

 44 ft in length, whilst the transformed spongy cells are 63 to 107 ft in 

 length. The mycelium ramifies throughout the cells of the attacked 

 areas. 



The ^cidia are very deeply sunk, long tubular structures, the 

 portion sunken beneath the level of the epidermis being about 0*756 m.m. 

 in length and about 0*190 m.m. in diameter. Each aecidium is situated 

 on a minute papilla and is extruded only from the under surface of the 

 leaf, never from the upper. That portion of the secidial fruit which 

 projects freely beyond the level of the epidermis is about 1 to 2 m.m. 

 in length. 



The peridium consists of a single layer of cells, the lower ones 

 being more elongated than the upper. Those situated about the middle 



