22 PROCEEDINGS OF THE AMERICAN ACADEMY. 



The appendage is very uniform in type, clearly distinguished above its 

 basal cell : the terminal cell bearing distally a single antheridium, which 

 is furnished with a spinous process ; the subterminal cell is sterile in all 

 cases ; the cell next below producing, normally, from one to three anther- 

 idia laterally and somewhat irregularly ; the antheridia being of charac- 

 teristic form with large appressed venters and stout necks curved outward. 

 Although in the single type the cavity of the perithecium appears to be, 

 as was formerly stated, continuous with that of the stalk-cell, as in genera 

 like Dimorphomyces, this is certainly not the case in the new forms de- 

 scribed below, the basal perithecial cells of which are clearly defined. 

 As it is highly improbable that A. Corticariae differs from other species 

 in this respect, it may be assumed that the basal cells in the unique type 

 are obscured by the abrupt curvature of the type specimen in this region. 



Acompsomyces Atomariae nov. sp. 



Colorless or very faintly brownish. Receptacle short, the distal cell 

 squarish ; the basal cell twice as large, narrow below, bulging beneath 

 the base of the antheridial appendage from which it thus appears to arise 

 terminally. Basal cell of the antheridial appendage rather long- and 

 narrow, not distinguished from the receptacle, to the distal cell of which 

 its lower half is closely applied, while its upper half is in equally close 

 contact with the stalk-cell of the perithecium ; the rest of the appendage 

 free, compact, slightly inflated, with evenly curved outline, faintly tinged 

 with brown, consisting of three cells : the lower subtriangular in outline 

 with the largest angle outward, bearing distally three closely appressed 

 antheridia neither of which arises from its outer side ; the cell next above, 

 somewhat larger, sterile, subtriangular with the largest angle external ; 

 the terminal cell smaller, separated by a horizontal septum from the 

 terminal antheridium, the neck of which is curved inward, the spinous 

 process conspicuous and external. Stalk-cell of the perithecium well 

 developed, rather slender, about as long as the receptacle, the basal cells 

 well distinguished : body of the perithecium narrower below, its inner 

 margin nearly straight with slight constrictions at the septa, the outer 

 bulging distinctly and more or less symmetrically ; the tip distinctly but 

 not abruptly distinguished, short, stout, slightly but rather abruptly ex- 

 panded below the flat-conical apex, from the middle of which project 

 abruptly the small short appressed prolongations of the lip-cells, forming 

 a terminal apiculus. All the cells thick-walled. Spores very slender, 

 44 X 3/x. Perithecia 36-46 X 25-30 /a, the stalk-cell 25-30 X 10 /i. 



