238 
Transactions of the Royal Society of South Africa. 
fectly described, or type not sliowing thyriothecia ; 4 species previously 
described. 
Sub-genus Clypeolaster. — 1 new species ; 2 new varieties ; 3 species 
previously described, and 2 species recorded from Brazil. 
The limits of the genus Asterina are not at all sharply defined ; the 
typical form of the thyriothecium is the flattened hemisphere, but not infre- 
quently elongated thyriothecia occur amongst the hemispherical ones ; the 
round Asterina thyriothecia graduate into the linear Lemhosia form, and in 
some species it is difficult to decide which is the predominating type. The 
chief distinction between these genera, apart from the shape of the thyrio- 
thecium, is that in Lemhosia the asci are elliptical or cylindrical, and para- 
physate, while in Asteri7ia they are more or less spherical, and in the 
sub-genera Bimerosporium and Glypeolaster they are aparaphysate ; but this 
character does not serve to distinguish the genus Lemhosia from the genus 
Parasteriiia, which also has paraphysate asci. 
On the other hand, the thyriothecia often approach the sub-spherical 
form of Englerulaster ; in the latter genus the cells of the thyriothecial 
membrane fall apart from the centre outwards, with abundant formation of 
mucilaginous matter ; in some species of Asterina the central cells break 
down in a very similar way, but the process does not extend outwards to the 
circumference ; the dividing line between the genera Asterina and Engleru- 
laster is, therefore, not at all sharp. 
The same applies to the genera Asterina and Asterinella ; the Asterina 
sj^ecies with regular node-cells approach very close to the Asterinella species 
with more or less torulose mycelium. The genus Seynesia, which is an 
Asterina without persistent mycelium, is only represented by one species, 
and so also the genera Microthyrium, Amazonia and Morenoina. In the 
genus Lemhosia three species are described, of which only one has been 
previously recorded ; none of the four species of Asterinella described agree 
with any of the species mentioned in Theissen's monograph of the genus. 
Morenoella, which differs from Lemhosia only in the absence of paraphyses, 
is represented by one species hitherto undescribed. Englerulaster Gymno- 
sporiae was included in a previous paper (11) in the genus Dimerium ; of 
the other two species now described, one has only been recorded from North 
America, and the other is apparently new to science. 
Geographical Distribution, etc. 
It has been pointed out in connection with the genus Asterina that a 
large proportion of the described species are South American, and this is 
equally true of the other genera of the Microthyriaceae, but whether this 
indicates that there are actually a larger number of species in South 
America, or that more complete collections have been made there than in 
Africa, remains to be proved. 
