POLYPORALES 443 



highly developed pileate forms similar to the higher Polyporaceae and 

 Agaricaceae. The ontogeny has not yet been studied. Irpex with 

 flattened teeth and Hydnochaete, a segregate from Irpex with setae in the 

 hymenium, have many points in common with Polystictus, and have 

 frequently been considered genera of the Polyporaceae. 



In the resupinate stage, the simplest form, Caldesiella, corresponding 

 to Hypochnus of the Corticiaceae, is of loose, floccose texture with 

 rough, colored spores and conical teeth with fimbriate tips. Correspond- 

 ing to Corticium, Grandinia has small obtuse spines covered with a 

 hymenium, while in Ada the spines are conical. In Grandinia crustosa 

 (Odontia crustosa) bulbils like those reported for the Corticiceae, were 

 observed by Hotson (1912). Ada omnivora (Hydnum omnivorum) has 

 been reported by Shear (1925) as the probable perfect stage of 

 Phymatrotrichum omnivorum (Ozonium omnivorum) the Texas root rot 

 of cotton. Kneiffia is characterized by its gelatinous consistency and 

 its sterile hyphal pegs which tower above the hymenium, as in Epithele. 



In Odontia, Hydnopsis and Radulum the projections of the hymeno- 

 phore are more highly developed. In Odontia (spores white) and Hydnop- 

 sis (spores colored) the spines are sterile at the tip and cystidia are present 

 in the hymenium ; in Radulum the spines are blunt knobs often confluent 

 and scattered irregularly over the fructifications. In Mucronella the 

 crust is fugacious and the spines are several millimeters long, appearing 

 deceptively like independent fructifications. 



In Phlebia the hymenophore is divided by uneven wrinkles which 

 are partly irregular and partly arranged in regular folds or ribs. In 

 many species, e.g., P. merismoides which forms orange- yellow or flesh- 

 colored crusts on fallen cherry, the hyphae break up into large masses of 

 ellipsoid oidia which develop in nutrient solutions to mycelia (Brefeld, 

 1889). 



In Merulius, the end member of this developmental series, the reticu- 

 lations are more highly developed and often suggest the pores of the 

 Polyporaceae, but the ontogeny is fundamentally different (Burt, 1917). 

 In Merulius the fertile hymenium is at first plane; by further growth, the 

 surface is thrown into folds and becomes porose but the hymenium con- 

 tinues to cover the edges of the pores. In Poria of the Polyporaceae, 

 the formation of pores precedes the development of the hymenium. 

 Later a hymenium develops in each pore, as in Porothelium, but these 

 hymenia are not continuous over the edges of the dissepiments. 



The lower forms are floccose and resupinate, as M. pinastri, with 

 spines in the corners of the reticulations so that it was earlier included 

 among the resupinate species of the Friesian Hydnum. Merulius lacry- 

 mans (Gyrophana lacrymans, M. domesticus) , so called because its myce- 

 lium is guttiferous in moist situations, is of great economic importance 

 in Europe as a dry rot of timber, although rare in America. Its 



