282 



MONOGRAPH OF THE LABOULBENIACEiE. 



DICHOMYCES Thaxter. Plate VI, figs. 25-36 ; Plate VIII, figs. 11-14. 



Proc. Am. Acad. Arts and Sci. Vol. XXVIII, p. 183. 



Receptacle flattened, sub-triangular ; consisting of a single basal cell followed by three trans- 

 verse series of cells symmetrical!}- placed ; the distal row bearing a pair of perithecia symmetri- 

 cally placed ; or a single perithecium, the fellow of which is undeveloped, together with certain 

 sterile appendages ; the sub-distal row producing a pair of compound antheridia symmetrically 

 placed and subtended by one or more sterile appendages. Perithecia symmetrical. Spores once 

 septate. Appendages and antheridia as in Peyritschiella. 



This genus, although very closely related to Peyritschiella, is distinguished by the bilateral 

 symmetry which characterizes not only the arrangement of the cells of the receptacle itself, but 

 of the organs produced from it, namely, the antheridia and perithecia ; although in a single 

 species incequalis~) one perithecium only is developed, which is, however, placed symmetri- 

 cally in relation to the cell from which, in the other species, a second perithecium arises. 

 Apart from this bilateral symmetry, the structure and development of the members of the two 

 genera are identical, and were it not for the fact that of the eight species included by them, four 

 correspond exactly to one, and four to the other type, the two genera might readily be united. 

 The four species of Dichomyces are among the most striking and curious in form of all the 

 Laboulbeniaceas. They have been found thus far only on beetles belonging to the Staphylinidae, 

 such as inhabit rather dryer situations, in most cases common among rubbish in cultivated fields. 



In the following descriptions the face bearing the antheridia is spoken of as anterior. 



Dichomyces fdrciferus Thaxter. Plate VI, figs. 25-29. 



Proc. Am. Acad. Arts and Sci. Vol. XXVIII, p. 184. 



Receptacle consisting of a small basal cell, which is nearly hyaline distally and suffused with 

 brown basally, the receptacle above gradually expanding into a more or less fan-like form, the 

 basal portion wholly black and opaque, the blackened area extending upward externally and 

 including a prong-like projection wilh one or two appendages at its base, which extends above 

 the base of the perithecium and forms the terminal portion of the sub-distal transverse series of 

 cells on either side ; the latter, seven in number, becoming generally suffused with blackish 

 brown, the long rectangular median cell usually more or less distinct, the remainder partly or 

 wholly opaque and indistinguishable; the antheridia lighter brownish. The distal row of cells 

 seven in number, their septa straight, thin, and clearly defined ; the middle cell of the series 

 bearing distally two appendages, placed antero-posteriorly, the terminal 'cells of the series on 

 either side also bearing two appendages, the inner slightly anterior. Perithecia bent slightly 

 forward, tapering very slightly to the blunt apex, which bears a short, recurved, tooth-like pro- 

 jection on either side from each anterior lip-cell. The perithecia and distal row of cells faintly 

 tinged with reddish purple. Appendages short, simple, hyaline, cylindrical, with a constricted 

 blackish base. Perithecia, 63 x 16-18 /j.. Receptacle: length to base of perithecia about 90 n; 

 to tips of external projections, 100-120 /x; greatest width, 55-60 /x. 



On Philonthus debilis Grav., Waverly, Mass., and Kittcry Point, Maine. 



