4 



Mycologia. 



diameters. In the trama it is not uncommon to find them without 

 cross walls and only infrequently branched. The diameter of 

 those of the trama varies from 3-4.5 fx, while in the subiculum they 

 are mostly 4-6 fx. 



Resupinate specimens of Poly poms tulipiferus and P. parga- 

 menus have considerable resemblance to these plants. This is 

 especially true of the former species in which the spores, especially 

 before reaching mature size, are quite similar to those of this 

 species. But in P. tulipiferus they are never obtainable in abun- 

 dance in crushed mounts of the hymenium as they are in P. am- 

 bigua. Moreover, that species has conspicuous incrusted cystidia 

 not difficult to find, and the diameter of the subiculum hyphae is 

 not as great as in P. ambigua. Neither are the peculiar inversely 

 conical tubes found in the former plant. From P. pargamenus the 

 spores serve as the best distinguishing character, for in that species 

 they are allantoid, 3-4 x 1 /x. The hyphae there are long and 

 straight in both trama and subiculum, with few or no cross walls, 

 unbranched, and the hymenium soon becomes decidedly irpiciform. 

 These conditions are quite at variance with those found in P. 

 ambigua. 



The distinctive characteristics of the plant may be said to be 

 the soft white growth, the inverted conical shape of some of the 

 tubes, the abundant spores, lack of conspicuous cystidia, and the 

 branched hyphae with cross walls but no clamps. 



American collections of this species have been compared with 

 authentic material kindly, furnished by Rev. Bresadola, the author 

 of the species, and they agree in all essential respects. The spore 

 measurements given by the author are slightly larger than I find 

 in both American and European material, but the difference is 

 negligible. Rev. Bresadola also states that cystidia are present in 

 the European plant, and on examining his material I find the same 

 condition of affairs as described above for American material. In 

 fact, the agreement of American and European material is in all 

 particulars much closer than is ordinarily the case between species 

 so widely separated. 



