78 BOTANICAL GAZETTE [jaxuary 



separation into two groups, although Fischer has contended, and still maintains, 

 that there is no intermediate type between the two groups; since if his suggestion 

 as to the interpretation of Choiromyces proves to be correct, this anomalous struc- 

 ture would indicate subsequent modification of the venae externae and not an 

 ontogenetic connection with the Plectascineae. 



:he 



finds is not related to Hyd\ 



Eutuberineae, but is generically identical with Geopora Harkness, which is closely 

 related to Hydnocystis Tul. The fruit body of Hydnocystis possesses a single large 

 hollow space which opens to the outside, though the opening is filled with hairs 

 The wall of the hollow space is clothed with the hymenium. Geopora is a Hydno- 

 cystis in which the hymenial walls are deeply infolded in an irregular and com- 

 plicated manner, in some species closed from the outside, in others communicating 

 in some places with infoldings of the external walls. All recent students of this 



HE 



Geopora here also, although he formerly placed these two genera among the Bal- 

 samiaceae, where they occupied an anomalous position. 



One of the very interesting forms proved to be the type of a new genus, Pseudo- 

 balsamia, which resembles Balsamia in external appearance, but differs in the 

 presence of venae externae which open to the outside, thus agreeing with the 

 Eutuberineae. It also differs from Balsamia in the absence of distinct trama 

 plates or veins {venae internae), or rather in the masking of them by the irregular 

 distribution of the asci among the tissue elements. In this latter character it 

 resembles the Plectascineae. The venae externae, however, are lined with para- 

 physes, and occasionally asci are found in this layer parallel with the paraphyses. 

 Pseudobalsamia, then, is regarded as one of the Eutuberineae, in which by secondary 

 modification the asci have withdrawn from their regular position in a hymenium 

 and have become intermingled with the elements of the trama, thus simulating one 

 of the characters of the Plectascineae, without showing any ontogenetic connec- 

 tion with that series. This leads Fischer to regard Hydnobolites, 

 placed by him in the Plectascineae, as one of the Eutuberineae, since the hymenium 

 has probably undergone a similar modification, and the venae externae open to the 

 outside. This view of the relationship of these two genera is strengthened by the 

 well-known fact that the asci are often distributed in the trama in certain species 

 of Tuber, as in T. brumale, and T. rufum; while Bucholtz has shown that in 

 the development of T. puberulum the tissue corresponding to the trama areas 

 (venae internae) become compressed and changed by the pressure of the develop- 

 ing asci. 



i 



The modification which Fischer's views on the systematic arrangement of 

 the ascomycetous Hypogeae have undergone as a result of this study are expressed 

 in a resume. Briefly this is as follows: 



. The Plectascineae series, with asci scattered in the tissue of the interior 

 of the fruit body, or in groups, not forming hymenia, includes the two families 

 Elaphomycetaceae and Terfeziaceae. In the latter family remain the genera 



former 



