i83 



hypophloeodal ; the algae, which are Chroolepus umbrina, are rather 

 sparingly scattered about the apothecium and still less sparingly 

 over the substratum or just beneath its surface. The hyphae are 

 slender and much branched with very indistinct septa, penetrating 

 deeply into the substratum. A hyphal branch enters into the inte- 

 rior of a cork cell through the small pores and destroys parts 

 of the cell-wall. The necessary mechanical protection to the thallus 

 is supplied by the superficial cork layers of the substratum which 

 are, however, broken here and there, thus allowing the thallus to 

 spread over the surface. The hyphae are intimately united with the 

 algae, but I have not been able to find any evidence that they pene- 

 trate the algal cell-wall. 



The apothecia are very striking in appearance. They resemble 

 in all respects a miniature volcanic crater {T. lefadinnni) ; this 

 character alone will enable one to recognize the genus ; they are 

 usually very numerous, quite uniformly scattered over the thallus, 

 and begin their development below the surface of the substratum, 

 somewhat more superficially than in Pyrenula and Tryfethclium. 

 The superimposed corky tissue is forced upward by the hygroscopic 

 paraphyses. At an early period the spores begin to form, and at 

 maturity are of considerable size. The exciple early in the history 

 of the apothecial development separates from the rigid cone formed 

 by the corky cells and the hyphae, and at maturity the hypothecial 

 disk alone remains attached to the substratum ; the inflexibility of 

 the cone and the alternate loss and gain of water of the thecium 

 causes the separation of the greater portion of the perithecium. In 

 the dry state the excipular fringe is plainly visible within the hollow 

 of the cone ; on the absorption of moisture the excipular margin is 

 forced against the sides of the cone, which projects above the disk 

 and the excipular margin. The paraphyses are long, simple, slen- 

 der and highly hygroscopic. The absence of color throughout the 

 •entire plant is noteworthy. 



The spores are large, multilocular, colorless, long spindle-shap- 

 ed, with a rather thick gelatinous outer wall, which is more or less 

 rugose, particularly in T. lefadinum. 



The above generic description is taken from T. lefadinum, which 

 is, perhaps, the only species occurring in the territory. 



The representatives of this genus have a decidedly southern 

 range and grow upon the bark of various trees. 



H 



