MONOGRAPH CF THE LABOULBENI ACE^E. 



283 



A most singular plant looking like a tvvo-pronged fork or a pair of inverted pincers, between 

 the black arms of which arise the two perithecia. The lower portion of the receptacle is so opaque 

 that the cell structure is indistinguishable ; but, as far as it can be made out, the lower trans- 

 verse scries of cells consists of a long median cell, on either side of which two, perhaps three, 

 cells are cut off in a fashion similar to that represented in the figure of D. princeps (Plate VIII, 

 figs. 11-12). In the present, as well as in the remaining species, the appendages vary somewhat 

 in number according to the number of terminal cells in the distal and sub-distal series, which is 

 not quite constant; and, in the majority of individuals, but few of the appendages remain 

 unbroken at maturity. Of the two appendages situated between the perithecia, one represents 

 the original terminal appendage of the germinating spore. The general form of the receptacle 

 is quite characteristic, and in the region of the distal series of cells it is distinctly concave on the 

 anterior side, the posterior face being somewhat convex. 



From the fact that its host is dark-colored, while the parasite itself is partly blackened, it is 

 often very difficult to detect, lying, as it generally does, appressed against the surface of the 

 former. It sometimes occurs, however, in such large numbers that it is seen without any diffi- 

 culty, and in such cases, although it is usually found on the under surface of the abdomen, it 

 may extend to the legs, thorax and all parts of the body of its host. Its natural position 

 seems to be with the tip of the perithecium turned toward the extremity of the insect's body, and 

 the anterior face turned inward, the perithecia being turned slightly backward (upward). 

 Although the host is very common, this species, like its relatives in the genus, seems to be 

 decidedly rare. 



Dichomyces in.iEQUalis Thaxter. Plate VI, figs. 30-34. 



Proc. Am. Acad. Arts and Sci. Vol. XXIX, p. 103. 



Receptacle as in D. fur ciferus, its fork-like projections prominent and indistinctly septate, 

 the distal row of cells bearing a single perithecium ; otherwise symmetrical, except that the sub- 

 median cell, above which a second perithecium arises in D. furciferus, is much reduced in size. 

 Appendages ten to twelve, one external to and near the base of each antheridium, two above the 

 median cell of the distal row, and three to four borne one from each of the three to four cells of 

 the distal row external to the sub-median cells, all arising as in D. furciferus. Perithecium large, 

 slightly inflated towards the base ; or sub-cylindrical, tapering abruptly at the extremity to a sub- 

 truncate apex destitute of appendages. Spores, 26 x 3.5 /j.. Perithecia, 100 x 25 //.. Receptacle, 

 length to base of perithecium, 92 /u.; length to tips of lateral forks, 110-130/x; greatest breadth, 

 50-60 fi. Total length to tip of perithecium, 180-190 /x. 



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



This species occurs, sometimes in company with D. furciferus, on the abdomen, more rarely 

 on the legs and thorax of its host. It is at once distinguished by its solitary perithecium, 

 which is destitute of the terminal outgrowths peculiar to the last named species. It is much 

 more common in the localities mentioned than its ally, and in none of the numerous 

 specimens examined docs there appear to be any variation in the points of structure which dis- 

 tinguish it. In no instance was any attempt observed to produce the usual pair of perithecia, 

 and the single perithecium, by its larger size, somewhat different form, and abruptly truncate 

 apex, serves readily to distinguish it. 



