CHAPTER V.—COMPARATIVE REVIEW.—ASCOMYCETES. 187 
later page, require a more searching investigation. But even if there are some 
exceptions to the rule, and a good many cases require further examination, the 
prevailing rule undoubtedly is that the two constituents of the sporocarp though 
close to one another are independent in their origin and growth. 
Eremascus, a typical Ascomycete of the simplest form, recently described by 
Eidam, is remarkable for the entire absence of an envelope-apparatus. 
Three chief forms of sporocarp in Ascomycetes may be distinguished according 
to the arrangement and conformation of its two constituent parts, and the coarser 
structure which results therefrom: the discocarp or apothectum and the pyrenocarp 
or perzthecium, which are used to distinguish the Discomycetes from the Pyrenomycetes, 
and the clecsfocarp, a form which remains closed. I use the words apothecium 
and perithecium in the sense introduced by P. A. Karsten in his Mycologia fennica. 

FIG. 8. A Usneabarbata, B Sticta fulmonacea. Portionsof thallus. a apothecia, / point of attachment to the 
substratum, After Sachs. Natural size. 
There are a few forms or small groups which cannot in strictness be arranged 
under one of these three types, but must be placed along with them as peculiar 
and exceptional cases. The accounts which we possess of the history of the 
development, though imperfect, are sufficient to show that the above types are 
distinguished more by habit in their advanced states than by any more fundamental 
distinction. 
Section LX. The distinguishing feature in the apothecium (Figs. 86-89, see 
also Figs. 19, 22, 85, and 99) is, that the hymenium lies exposed on the surface 
of the sporocarp while the spores are forming and maturing. The hymenium 
itself, the discus, lamina proligera and sporigera of the old terminology, consists 
first of the ascı, secondly of capilliform hyphal branches, the paraphyses---The 
