134 



timate organic association between hyphae and algae. The algae 

 are also very numerous for such a lowly organized thallus. 

 The species occur on tree-trunks and mosses. 



PLATE 15. fig. 4. 



BlLIMBIA FAGINEA Kbr. 



Paraphyses and spore-sac with spores. 



5. Bacidia De Not. Giorn. Bot. It. 2 : 189. 1851. 



The general characters of this genus resemble those of Biatora, 

 but it is distinguished by the acicular colorless 4-10-septate spores, 

 which are rather irregular in size and form, one end being usually 

 pointed while the other is blunt and variable in diameter ; they are 

 also frequently curved and twisted. 



The apothecia are of medium size, disk more or less convex to 

 flattened and varying in color from light brown to black ; the 

 thecium is also more or less colored, usually yellowish brown ; the 

 hypothecium varies from dark brown to nearly black. 



The thallus is typically crustaceous, sometimes becoming indis- 

 tinctly areolate or coarsely granular with a grey or greenish color. 

 As far as I have been able to observe, the algae are constantly Cysto- 

 coccus humicola, and are intimately associated with the haustorial 

 branches. 



In several respects this genus presents degenerate characters. 

 The paraphyses are granular ; the spores are variable in size and 

 form, as well as deficient in number and indistinct in outline. This, 

 however, does not imply that this group presents any degenerative 

 tendencies as lichens. The spores tend to degenerate because they 

 are perhaps of little or no value in reproduction. Soredia are of fre- 

 quent occurrence in this genus, in this respect resembling Bilimbia. 



Quite a number of representatives of this genus occur in the 

 eastern United States usually growing upon the bark of trees, rarely 

 upon moss and rock. It is southern in its general range. 



PLATE 18. 



Bacidia umbella (Pers.) Mass. 



1. Plants natural size. 



2. Apothecium and portion of thallus magnified. 



3. Section of apothecium. 



