Ca@oma. 261 
On Mercurialis perennis. 
May and June. 
BioLocy.—This is stated by Rostrup and Nielsen to be the 
fEcidium of Melampsora tremule from Populus tremula and alba. 
I repeated their experiments by placing the teleutospores from P. ¢re- 
mula on Mercurialis perennis on several occasions, but was unable 
to confirm their statement. The Ceoma pinitorguum, which these 
authors also state to be connected with a form of 47. tremule, has 
not yet occurred in Britain. 
In October, 1887, however, during the annual excursions of the 
Woolhope Club, I gathered a number of leaves of Populus alba, on 
Dinmore Hill, with a Melampsora on them. In April and May, 1888, 
I infected with this Melampsora some plants of Mercurialis perennis, 
which had been growing for several years in my garden at King’s 
Lynn, and produced first the spermogonia, and then the perfect Cecoma. 
Czoma alliorum. Link. 
Spermogonia flat, yellowish, in circular groups. Sori amphigenous 
in circular or elliptical clusters. Spores subglobose or ellip- 
tical, punctate, yellow, 17-25 x 10—-20p. 
Synonyms. 
Caoma alliatum. Link (?), “Sp. Plant.,” vol. ii. p. 43. 
Uredo alliorum, D. C. Cooke, “ Micro. Fungi,” 4th edit., 
p- 217, in part. 
On Allium ursinum, oleraceum, vineale. 
B1oLoGy.—Schréter thinks this species, or at least the form of it 
that occurs on A. oleraceum, is connected with Melampsora populina 
(“ Krypt. Flor. Schl.,” vol. iii. p. 363). 
Czoma orchidis. Alb. and Schw. 
Spermogonia on yellowish spots. Sori generally irregular, flat, 
often confluent. Spores subglobose or ovate, punctate, yellow, 
15-25 X 10-204. 
Synonyms. 
Winter, Zoe. cit., p. 256. 
Uredo confluens, var. orchidis. Alb. and Schw., “ Consp.;” 
p. 122. : 
