ORDER PSEUDOSPHAERIALES 295 



stromata in the brown vegetative mycelium on the surface of the host. 

 (Fig. 95.) 



Family Trichopeltaceae. The conspicuous mycehum is radial in 

 arrangement, or forms sterile parallel hyphae. The cover of the stroma 

 appears to be merely a local thickening of the vegetative mycelium. 

 Paraphy sis-like threads are lacking. Six genera are known and from 10 to 

 15 or more species, all tropical. 



Family Hemisphaeriaceae. Mycelium lacking or reticulate, super- 

 ficial. Cover of the stroma not radial in structure. Under the cover there 

 may be a single hymenium with or without paraphysis-like threads or 

 several smaller hymenia may be produced under one cover. In some cases 

 these are reduced to a considerable number of "monascous hymenia," 

 i.e., embedded in the hypothecium are scattered single asci. Nineteen 

 genera of mostly tropical fungi. Micropeltis occurs in the Old and New 

 World tropics on leaves. Its stroma contains a single hymenium with 

 many asci and with paraphysis-like structures and with hyaline asco- 

 spores of four or more cells. 



Order Pseudosphaeriales. The fungi included in this order have 

 been segregated from the Sphaeriales, Perisporiales, and Dothideales, 

 mainly, and even from the Pezizales. Their true relationship is not known; 

 indeed it is doubtful whether all the genera assigned to this order are 

 really related. They are largely tropical, but many occur in temperate 

 regions. They may be parasitic on plants or even on insects, or sapro- 

 phytic. The fruiting bodies resemble superficially the perithecia or stro- 

 mata of the Sphaeriales or some Dothideales. They are almost external or 

 at least their tops become external by rupture of the host tissues. They are 

 distinguished from all the preceding orders (except a few species of the 

 Hemisphaeriaceae with "monascous hymenia") by the mode of occur- 

 rence of the asci. These arise in separate stromatic cavities, one ascus to 

 each cavity. In the majority of genera they are oblong or nearly spherical 

 and mostly eight-spored. They appear to develop somewhat as follows: 

 Within a pseudoparenchymatous stromatic structure arise branching 

 ascogenous hyphae, probably — in many cases, if not in all — from an- 

 ascogonium. These hyphae grow out into the stromatic tissue, dissolving 

 it so that eventually each terminal ascus lies in a cavity of the original 

 sterile tissue. These asci may be separated rather widely or the separating 

 tissue may be but a thin sheet of cells. The developing asci may arise in a 

 fan-shaped cluster destroying the stromatic tissue as they enlarge. The 

 ascospores vary from hyaline to brown and from one-celled to many- 

 celled, in many genera being muriform. The fact that the many-celled 

 type of ascospore is the most typical for the order, the one-celled hyaline 

 spore being found only in two genera of the supposed transitional family 

 Dothioraceae, casts doubt upon the idea that the Pseudosphaeriales are 



