Durand: The Genus Keithia 
7 
under the name Stictis Tsugae.* Examination of authentic ma- 
terial has shown it to belong in Keithia rather than in either 
Stictis or Propolidiiim, to which it was referred by Saccardo. 
The genus Keithia, therefore, is known to possess three species, 
all of which are parasitic on the leaves of conifers. One is on 
Junipertis, in Europe, the others on Tsiiga and Thuja, respec- 
tively, in America. 
Phillips and others have referred the parasite of juniper to the 
Phacidiaceae on account of its dark color, and its supposed lacin- 
iate method of dehiscence. Maire and Saccardo in describing the 
genus Didymascella (later regarded by Maire as a synonym of 
Keithia) remarked that it certainly belongs nearest to the Pha- 
cidiaceae. So long as knowledge of the genus was confined to 
the originally described species such a reference seems not at all 
remarkable. Eurther study of the group, especially of the two 
American representatives, throws a somewhat different light on 
its affinities, and seems to indicate that it might better be referred 
to the Stictidiaceae. Maire has pointed out, with good reason, 
that in the case of K. tetraspora the fungus itself does not split 
in a laciniate manner, but that the lobes are really formed of the 
epidermis of the host, which is ruptured by the expanding ascoma 
beneath. 
There seems little room for doubt that the three species here 
included in Keithia are congeneric. The habit, all being parasites 
of coniferous leaves; the erumpent ascomata bursting the epi- 
dermis only; the uniformity of structure of the poorly developed 
excipulum ; the small number and peculiar septation and color of 
the spores, all indicate that we are dealing with a very compact 
group. Comparison of these three species shows that in the case 
of K. thujina and K. Tsugae the color is much brighter than in 
K. tetraspora, and the covering epidermis is thrown off as a scale 
rather than splitting stellately. When completely moist the ascoma 
becomes somewhat elevated and cushion-like. The general re- 
semblance of these plants to Propolis faginea is so great that it 
seems that they must be associated in the same family. Sections 
show that in all species of Keithia the excipulum and hypothecium 
are very poorly developed, but certainly are not lacking as stated 
‘Appalachia 3; 245. 1883. 
