262 INTRODUCTION TO THE STUDY OF FUNGI 



branched, instead of remaining simple. More recently the 

 genus Phoma has been subjected to another mechanical sub- 

 division into Phoma and Macrophoma, the latter to include all 

 the species of Phoma which have sporules exceeding a definite 

 size, so that the determination of the genus may 

 9 depend upon the difference of a micromillemetre. 



& ^ Another genus, Asteromella, which is equal to 

 Asteroma, minus a subiculum, has the minute 

 perithecia clustered on dendritic spots. There are 



five or six smaller genera, consisting of but a 

 Pig. 121.— Peri- . & . ' . 5 . 



thecium of tew species, which completes the series of genera 



Phoma with j n w hi c h the perithecia are not rostrate. In 

 Sphaeronema the habit is that of Phoma or 

 Aposphaeria, but the perithecia are rostrate. In addition to 

 these follows a series of genera in which the perithecia are 

 seated upon a subiculum of some kind, more or less distinct 

 and definite. In Chaetophoma the perithecia resemble those of 

 Phoma, but are innate in a dematioid subiculum resembling 

 Fumago or Asterina. An allied genus, Asteroma, is the ana- 

 logue of such genera as Asterina or Dimerosporium, the minute 

 perithecia being seated upon, or amongst, a subiculum of radiat- 

 ing black fibrils. In the remaining two genera, Ypsilonia and 

 Cicinnobolus, each contains but a single species, and the latter 

 is parasitic upon Oidium. In the three genera which com- 

 plete those in which the perithecium is bare, Neottiospora has 

 the sporules cristate, and the other two genera have the 

 sporules in chains. We pass now to the smaller series, in 

 which the perithecia are hairy or bristly. Here are four 

 genera, the most numerous and important of which is 

 Vermicularia. In habit the perithecia resemble those of 

 Venturia, or some species of Chaetomium, the long dark 

 bristles are septate, and the sporules mostly curved. Pyreno- 

 chaeta is similar, but the hairs of the perithecium are shorter, 

 and the sporules ovoid or oblong. Muricularia and Staurochaeta 

 differ from the foregoing in the character of the external hairs. 

 This brief review of the simple species leads us to the series 

 in which the perithecia are composite or caespitose, usually 

 with a definite stroma. Dothiorella resembles superficially 

 either Botryosphaeria or Cucurbitaria. The pustules are 



