SPHAERIACEAE 59 



cespitose or composite in a stroma; asci typically clavate to cylindric and persistent, 

 sometimes stalked, usually 8-spored but the spores varying from one to many, with 

 paraphyses or paraphysoids, or these lacking; spores from minute botuliform to 

 long filiform, hyaline to dark, continuous to septate. 



This is the typical order of the Pyrenomycetes and the one in which evolution 

 has been the most active. In contrast to the ancestral Perisporiales, saprophytism 

 has been developed in a high degree, accompanied by the sinking of the mycelium 

 and the specialization of the perithecium for spore protection and distribution. In 

 one direction this has produced the carbonous wall, in the other a fleshy one, both 

 of sufficient thickness to necessitate the regular development of an ostiole for 

 freeing the spores. 



This order is distinguished from the Perisporiales primarily by the presence 

 of an ostiole, typically in the form of a perforate papilla or beak. As a rule, the 

 mycelium is immersed instead of superficial, and is often developed into a stromal 

 mass about the perithecia. The persistence of the perithecial wall in the stroma 

 separates it from the Dothideales, in which the perithecia have become locules 

 enclosed merely by stromal hjphae. This evolution has apparently taken place in 

 two directions, the massive stroma giving rise to the Dothideae and the clypeus 

 to the Phyllachoreae. The modification has been so gradual and continuous that 

 the number of intermediate forms is large and these must be sought in both orders. 

 The sphaerials with paraphysoids approach the Myriangiaceae to a certain degree, 

 but it does not seem probable that they are phyletically connected. The Microthy- 

 riales are set apart by the dimidiate and typically radiate ascoma, and usually also 

 by the superficial mycelium and fruit-body. 



Key to Families 



A. Perithecia not parasitic on algae, without a 



thallus 



1. Perithecia dark, membranous to carbonous 



a. Ostiole papillate or conical, round, not com- 



pressed Sphaeriaceae p. 59 



b. Ostiole broad and compressed, the opening 



linear Lophiostomaceae p. 82 



2. Perithecia bright-colored, rarely whitish, fleshy Hypocreaceae p. 76 



B. Perithecia parasitic on algae, typically with a 



thallus Verrucariaceae p. 84 



C. Ascomata at first perithecioid, then cupuloid, in a 



ramose or alveolate stroma Cyttariaceae p. 83 



Family 26. SPHAERIACEAE 



Perithecia innate, erumpent or superficial from the first, typically globoid, 

 sometimes lentiform, or cupulate-collapsing, rarely conical or cylindric, regularly 

 ostiolate, rarely astomous, sometimes beaked, wall typically dark, brown to black, 

 membranous, coriaceous or carbonous, never fleshy and bright-colored, frequently 

 hairy, separate, cespitose or composite in a stroma; stroma scanty and immersed, 

 or producing a subicle or stroma of various forms; asci typically clavate to cylindric 

 and persistent, mostly 8-spored, paraphyses or paraphysoids present or sometimes, 

 lacking; spores various. 



The first four families are intimately related, the line of descent being con- 

 tinuous from the central sphaerials to Hypocreaceae and Lophiostomaceae. In the 

 case of the former, whitish or hyaline forms are scarcely to be distinguished from 

 innate membranous sphaerials, and a similar difficulty recurs in those genera with 

 fleshy-leathery stromata. The thick compressed ostiole with a rimose opening 



