Robinson. — Notes on the Genus Taphrina . 167 
II. Mycelium spreading itself just below the cuticle, and 
not entering the tissues of the host. 
(a) Asci with stalk-cells, 
T. alnitorqua^ Tul. 
( b ) Asci without stalk-cells, 
T. aurea (Pers.), Fries. 
T. caerulescens (Mont, et Desm.), Tul. 
For Exoascus Wiesneri, Rathay, and Ascomyces Quercus , 
Cooke, see Taphrina deformans and T. caerulescens re- 
spectively. 
T. Pruni (Fuckel), Tul. 
Exoascus Pruni , Fuckel, Ennumeratio Fungorum Nas- 
soviae, p. 29. 
This species occurs frequently in the United States upon 
Prunus domestica^ L., and causes a peculiar hollow deformity 
of the fruit, the so-called ‘plum-pocket’ (Narren-Taschen). 
Late in June the infected plums reach almost their mature 
size, but consist merely of a thin shell having instead of 
pulp and stone only a few threads stretched irregularly across 
the cavity within. A Taphrina, , probably identical with this, 
attacks several of our native species of Prunus , and has been 
found on P . maritima , Wang., Dartmouth, Mass., on P. 
virginiana , L., near Lake Willoughby, Vt., and on P. sero - 
tina> Ehr., Cambridge, Mass. On the last-mentioned host 
the fruit, which is normally nearly spherical, when infected 
becomes elongated or even somewhat spindle-shaped, and 
early attains a size several times greater than at normal 
maturity. The stamens and floral envelopes also suffer 
hypertrophy and remain attached to the base of the fruit 
in an involucre-like mass. 
The asci are formed in very great numbers ; early in their 
development they break through and almost obliterate the 
cuticle, and form a dense and continuous layer over the 
whole surface of the fruit, which later becomes hoary from 
the escaping spores. In general form the asci are long and 
slender, cylindrical, truncated or rounded at the summit, 
