iqiq] briefer articles 267 



admirabilis Pk., in this laboratory, discovered the origin of this structure. 

 These prominent h\-phae are long, stout, subcylindrical cells, which arise 

 from the inner cells of the subhymenium and extend downward, con- 

 verging by their free ends against the trama, often compressing it into a 

 thin layer. In some species the free ends of these cells are subcapitate, 

 with a slight constriction below the capitulum. It is clear, therefore, 

 that these peculiar structures in the trama of the lamellae of PliUeus 

 and Valvar ia are internal cysj:idia of a special kind. They are different 

 in form from the other tN-pes of cystidia which project outward beyond 

 the surface of the hymenium in many species. The origin and develop- 

 ment of these internal cystidia will be described by Professor Walker 

 in a forthcoming paper on the development of Pluteiis admirabilis. 



The presence of these numerous internal cystidia, giving a distinct 

 structural aspect to the trama of the lamellae in Pluteus and Volvaria, 

 indicates that there is a very close phylogenetic relation between these 

 two genera. In both genera the stipe is separable from the pileus, and 

 the spores are of the same t\^e, being smooth, globose, or slightly 

 elongated. No true species of Annular ia have been examined in the 

 fresh condition to determine whether or not internal cystidia are present. 

 It cannot now be stated with confidence to which group it belongs, but 

 other morphological features indicate that it is more closely allied to 

 Pluteiis and Volvaria. In the other genera of the Rhodosporeae the 

 stipe is not separable from the pileus, the spores are angular, and these 

 peculiar internal cystidia are absent. 



In the Rhodosporeae, therefore, there are at least two distinct phyletic 

 lines. The relation of the genera to these two phyletic lines may be 

 represented as follows. 



I. Pluteinae. — Pileus easily separable from the stipe; lamellae 

 with numerous internal cystidia converging as they descend and some- 

 times nearly obliterating the trama by pressure; spores smooth. Plu- 

 teus and Volvaria {} Anntdaria) . 



II. Entolomatinae. — Pileus not separable from the stipe; lamellae 

 without numerous internal cystidia, trama normal; spores angular. 

 Entoloma, Leptonia, Clitopilus, EccUia, Nolanea, and Claudopus. — Geo, F. 

 Atkinson^ 



3 This paper was received from the late Professor Atkinson in January 1918. 



