20 
Sydow’s specimens (Mycoth. March. no. 2290), on Prunus 
Padus, are C. leucostoma 
Distrib. France, Holland, Germany, Italy, Denmark, Siberia, 
United States of America. 
C. occulta Sacc. Syll. iii. 258. Allesch. vi. 568. 
“Pyenidia nestling beneath the bark, connate; contents 
grey. Spores very minute, cylindrical, curved, 6 x 1-5 
expelled in golden tendrils from a common tuberculate 
pore.’ : 
On dry branches of Alnus glutinosa. Regent’s Park (Cooke). 
Apr. Very uncommon. According to Fuckel it is the pyecnidial 
stage of Melanconis occulta Sacc. Cf. Cytospora diatrypa, which | 
has not yet been found in Britain 
Distrib. Germany, Denmark. 
C. Oxyacanthae Rabenh. in Bot. Zeit. 1858. p. 503. Sace. 
Syll. iii. 255. Allesch. vi. 579. Died. p. 339. 
Stromata gregarious, but not very crowded, covered, when 
fully developed hemispherical on a rounded base, swollen, up 
to 1 mm. diam., bursting irregularly at the summit and showing 
a small disc, which is at first whitish, then when old blackish, 
marked with 1-3 inconspicuous black ostioles ; loculi numerous 
more or less labyrinthiform, but frequently arranged in a 
conspicuously radiating manner; walls dark-grey; central 
columella black, often very distinct; walls of conceptacle thick 
and blackish, walls of the loculi composed of a rather thin 
greyish-green tissue of narrow elongated cells. Spores 6-7 
{rarely 8) x 1-1-5 p, issuing as a white tendril; spore-mass 
whitish ; sporophores subulate, fasciculate at base, occasionally 
branched above, 15-25 x 1-1-25 (10-13 x 1p, Died.), springing 
-direct from the prosenchymatous wall at right angles. 
On dead twigs, and especially on hedge-cuttings and stakes; 
of Crataegus Oxyacantha. Abundant; Warwickshire; Worcester- 
shire; Cheshire; Ayrshire, &c. Frequently accompanied by a 
form of Valsa ambiens Sacc. No doubt very common, but mostly 
placed by collectors under C. leucosperma. Recorded abroad on 
Cydonia, Pyrus and Sorbus; also on Quercus, but this latter is 
doubtless a mistake. 
The epidermis is swollen by the mass of spores for some 
distance round the disc, so that the full grown pustules are not 
conical, but hemispherical. The disc may remain pale and 
pruinose at the edge. The tissue of the walls of the loculi is 
unlike that of many Cytosporas, being composed of long prosen- 
chymatous grey-green thick-walled cells, about 2°5 py wide, 
closely resembling those of the leaf of Hypnum seoneasnable 
By this it is easily distinguished from the otherwise similar 
C. ambiens, which has the walls of the pyenidia composed of. 
thick dark-brown parenchymatous cells. C. carphosperma is 
also very similar, but is distinguished by its host, and ni the 
yellowish colour of the freshly exuded tendrils. - ; 
