South African MicrotJiyriaceae. 
237 
breaks down from the centre, falling apart into separate cells, with abundant 
secretion of mucilaginous matter. 
The pycnidia {Aster ostomella) in the genus Asterina are usually identical 
in form with the thjriothecia, but they are smaller ; these were often 
mistaken by the earlier workers for thyriothecia, and described as such, the 
brown, continuous conidia being taken for ascospores and described as a 
separate genus Asteronia. Of the conidia of Aeterinella Theissen (3) says 
very little, but mentions conidia of the Asterostoraella type in one species, 
and in his key to the genera he includes the genus in the section with one- 
celled conidia. Of the four South African species one has conidia of the 
Asterostomella type, one has hyaline, curved, aseptate conidia, and in a third 
they are hyaline, fusiform and four-celled ; in each case they are borne in 
pycnidia resembling thyriothecia. 
In the genus Clypeolella the conidia are four-celled, and are borne on the 
mycelial hypliae ; more than one superficial fungus has been collected show- 
ing this type of conidium, but in every case the thyriothecia were very 
immature, so that it was impossible definitely to identify any one of them 
as a Clypeolella, and it is still uncertain whether this genus occurs in South 
Africa. 
The asci may be paraphysate or aparaphysate, and in some cases the 
presence or absence of paraphyses is used as a generic distinction ; they vary 
in form from elliptic or clavate to spherical. There is also considerable 
variety in the spore forms of the different genera, but in the majority they 
are two-celled, and either hyaline or brown. 
THE SOUTH AFEICAN GENERA. 
The genus Asterina Lev. has the largest number of species. In his 
monograph on this genus, Theissen describes 108 species, of which 55 are 
from South America ; he only records 6 genuine species from Africa. A 
much larger number of fungi has been described from South Africa as 
belonging to the genus Asterina, the greater part collected by MacOwan and 
Medley Wood, and described by Kalchbrenner and Cooke in Grrevillea ; a 
few were described at a later date by Winter, Hemiings, and Sydow, making 
22 species in all. Of these 11 are excluded as not belonging to the Micro- 
thyriaceae as now defined ; Theissen excludes a still greater number on 
account of the absence of thyriothecia in the type specimens, but a number 
of these I have fortunately been able to re-collect and re-describe. 
In the present paper 30 species of Asterina are recorded from South 
Africa, and are represented in the National Herbarium, Pretoria. These are 
as follows : 
Sub-genus Dimerosjoorium. — 13 new species ; 1 new variety of a Brazilian 
species ; 4 amplified descriptions of species previously recorded but imper- 
