SPHAERIALES 



47 



each other. A common saprophytic form of this type is seen in 

 the black conic papillae often found on the inner surface of the 

 halves of old peach stones long exposed to the weather ; these are 

 the scattering perithecia of a black fungus (Caryospora putami- 

 nuin, PL 4, f. /J, 16) which contain the large peculiar two-celled 

 spores. A common parasitic form of the same type is seen in late 

 summer on the leaves of hazel ; in this species (Mamiana coryli} 

 the black pear-shaped perithecia are separately located on definite 

 areas on the under surface of the leaf. 



In other species the perithecia may be united in a somewhat 

 woody stroma as in the numerous black or red brown tubercles of 

 Hypoxylon everywhere common on beech, birch, alder, oak and 

 many other woods ; other forms are seen in the smaller tubercles 

 erumpent through the bark of twigs and branches of woody plants 

 or in the persistent half woody stems of herbaceous plants. 



In some genera the mouth (ostiole) of the perithecia is flat, 

 while in others the perithecia become conic or even rostrate 

 (PL 4, f. if). In many cases the formation of conidia precedes 

 the development of the ascospores, and in a few of these there is 

 a superficial resemblance to fungi of the next class which has 

 deceived even botanists familiar with these plants. 



In a few cases where there is no definite stroma a black layer is 

 formed about the mouth of the sunken perithecia in the shape of 

 a rounded disc. This is known as the clypcus, and characterizes 

 an entire family. 



The families * may be separated as follows : 



I. Perithecia free, either without a stroma, partly sunken in a loose mass 

 of mycelium, or sessile above an imperfect stroma. 2. 



Perithecia sunken in the substratum, without a stroma, rarely united 

 above by a black tissue (clypeus). 9. 



Perithecia fully imbedded in a stroma, the mouths only projecting, or 

 becoming free by the breaking away of the outer stromatic layers. 13. 



* We have omitted generic synopses in this numerous order for several 

 reasons. ( I ) Because of their great number, which would unduly extend 

 the limits of a small work. (2) Because of the difficulty for a beginner to 

 distinguish closely allied genera, and (3) Because any one sufficiently in- 

 terested in the species will need the literature cited at the close of the sec- 

 tion, in which descriptions of the species as well as synopses of the genera 

 may be found. In spite of all that has been written, however, many of 

 our species are imperfectly known, even in their ascosporic stages, and 

 there is scarcely a genus that is not in crying need of a revision. 



