290 THE BASIDIOMYCETES 



shaped hymenium within the head. The family therefore has 

 been considered as the tremellaceous counterpart of the Phleoge- 

 naceae among the Auriculariales. The cytology of the basidia in 

 Hyaloria has been studied by Martin (1937), who finds that 

 their development is completely in accord with that of the 

 Tremellaceae. 



The family Sirobasidiaceae includes tremellaceous forms in 

 which the basidia are produced in chains. There is a single 

 genus, Sirobasidium, with two known species occurring on wood 

 in Brazil and Ecuador [Lagerheim and Patouillard (1892), Mol- 

 ler (1895)]. Both are gelatinous forms resembling Tremella in 

 general appearance, but with chains of basidia produced in basipe- 

 tal succession. In one species the basidium is similar to that of 

 Tremella; in the other, the basidium is divided by a diagonal sep- 

 tum into 2 cells and forms 2 basidiospores. Whether the 2 species 

 under consideration are actually cogeneric is doubtful. 



The Sirobasidiaceae, as exemplified by forms with obliquely 

 septate basidia, may easily have been derived from the Tremel- 

 laceae. In Trejnella liitescens [Coker (1920)], for example, the 

 septations are never longitudinal, as is characteristic of the order, 

 but may come to occupy oblique positions. Furthermore, the 

 proHferation of the basidia in the Sirobasidiaceae appears to be 

 foreshadowed by the condition in Clavariopsis prolifera and Seba- 

 cina prolifera [Rogers (1936)]. In the latter species clusters of 

 basidia are formed, each new basidium originating from a clamp 

 connection at the base of an earlier-formed basidium. 



Less certainly related to the Tremellales is a group of or- 

 ganisms comprising the family Tulasnellaceae. There are two 

 genera, Tulasnella with 11 species, and Gleotulasnella with 9 

 [Rogers (1933)]. According to Rogers' (1932) account of 

 basidial development in several species of Tulasnella, the hypo- 

 basidium is a non-septate structure. After nuclear fusion and 

 the usual 2 divisions, there appear 4 swollen epibasidia, into which 

 the nuclei migrate. Each epibasidium thereupon becomes sepa- 

 rated from the hypobasidium by a wall across its base. A third 

 mitosis occurs within the epibasidia, each of which ultimately 

 bears a binucleate spore. Rogers regards the Tremellales as hav- 

 ing been derived from the Tulasnellaceae through the formation 

 of septa within the basidium at an earlier stage in its develop- 

 ment. By many authorities, however, the "epibasidia" of Rogers 



