84 SALMON: SUPPLEMENTARY 
London, Canada, July, 1889 (J. Dearness).”’ These specimens ‘ 
show further the manner in which this form passes gradually into i 
the type: perithecia with a normal habit occur on both sides of 
the leaves; on the under side of the leaves about the midrib, We _ 
find perithecia congregated in patches with persistent mycelium; — 
and on the branches themselves the perithecia are crowded into ' 
dense patches among persistent mycelium. | 
Other examples of P. oxyacanthae occur in the United States — 
—on Crataegus punctata and other species of Crataegus, on Prunig — 
Virginiana, etc.—in which the perithecia are densely crowded i 
along the midrib of the leaf (although the aggregation is not que i 
so marked as in Thiimen’s plant), and in these cases it is t ie ' 
noted that the mycelium is subpersistent in exactly the same may 
ner as in ‘‘ var. vamulicola.” It may be observed that among the | 
forms of Sphaerotheca humuli the plant on Nedlia opulifolia, Ke ] 
(see monograph, p. 63), stands in the same relation to the type@ fF 
the ‘var. ramulicola’’ does not typical P. oxyacanthae. i 
In a specimen of P. oxyacanthae on Crataegus oxyacantha fom | 1 
‘ Belluno, Italy (Speg. 7/10 ’78),” the spores according to hades | 
ings by Spegazzini which are reproduced at Pl. 9, 7. 22,” are vet | 
strongly curved. In the specimen sent to me I was unfortunately 1 
unable to find any mature perithecia containing spores. The j a 
most allantoid shape of the spores shown in Spegazzini’s drawings 
is certainly remarkable ; although in P. oxyacanthae vat. tridat 
I have observed that the spores are sometimes slightly cul’ 4 
and in Arysiphe trina Harkn., the curving is more frequent 
more pronounced. ae 
In another specimen of Spegazzini’s collecting, from the same : 
locality and on the same host, the appendages reach from 2 ys — 
nearly 3 times the diameter of the perithecium. Such cam 
these show clearly the impossibility of keeping the P. 7)” tne 
Kunze and Schmidt apart from P. oxyacanthae. (See monoghs” 
Pp. 32.) 2 
Bailey (2**) refers the fungus known commonly in th 
States as the “‘ peach mildew” to the present species, and © 
“the peach mildew (P. oxyacanthae) has been serious in ¥# 
parts of western New York the past season. In the Niagalt 
* The plates will appear with the final part in the BULLETIN for March. 
e United 
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