109 
Fig. 
10. Empty conidium. 
11. Mass of zoospores just escaped and still fastened together. 
12. The same breaking apart. 
13. Zoospore swimming free. One cilia represented. Two or three doubt¬ 
fully observed. 
14. Zoospore rounded up and at rest. 
15. Zoospore germinating. 
16. Oospore in section, X 640. 
* Figs. 17-24, Peronospora hydrophylli, n. sp. 
17. Conidiopliore, average size, X 224. 
18. Mycelium, with haustoria and cells of the host penetrated by them, X 
224. 
19. Stomate, with five conidiophores extending from it, X 224. 
20,21. Oospores in section, X 640. 
22-24. Germinating conidia. 
SOME PERONOSPORACEAB IN THE HERBARIUM OF THE DIVI¬ 
SION OF VEGETABLE PATHOLOGY. 
By W. T. Swingle. 
Finding a number of interesting species of Peronosporacem in the 
herbarium of the Division of Vegetable Pathology, I have decided to 
report on all specimens there represented that have not been mentioned 
previously. I have included a number of interesting forms collected 
during the past year, but have excluded all specimens in exsiccati as 
they are already known to most students of the group. I have included 
every collection, even of the most common species, because the record of 
date and locality may, even in such cases, prove of value in the future. 
Every specimen has been examined for oospores and they have been 
reported whenever found. Nothing is mentioned in the paper that is 
not represented by a specimen in the herbarium. 
ALBUGO (Persoon,§)* 
S. F. Gray. A natural arrangement of British plants, vol. 1,1821 p. 540, No. v, p. 155. 
1801. Uredo § Albugo, Persoon. Synopsis method, fungorum, p. 223. 
1847. Cystopw, J. H.LAveille, Sur la disposition mdthodique des Ur6din6es. <Ann. 
des Sei.Nat., 3° s6r., Botanique, tome 8, Paris, 1847, p. 371. 
There seems to be no doubt that the generic name Cystopus must bo 
abandoned in favor of Albugo , which has twenty-six years priority. 
There can be no question as to the identity of the two genera. Gray 
includes Albugo in the subfamily Coeomidece which he describes thus: • 
Sporidia dust-like, free, heaped, sessile or pedicelled, one or many celled, growing 
at first under the epidermis of living plants, then bursting through it, naked or cov¬ 
ered with a false peridium or thecae formed of the epidermis of the plant on which 
it grows.* 
* Loc. cit., p. 532* 
16788—No, 2 -4 
