Til AXTKK. ■ MON()(JltAIMI OF TIIK 1A liOULH ION I A( ' K.K 



249 



In-low the antheridia, Plate LXXI, (ig. 5. II' this interpretation of Hie conditions is correct, the ba al 

 cell, from which, as in other compound antheridia, the antheridial cells arise as endogenous branchlefs 

 proliferating into the terminal cell,l)y its enlargement and elongation pushes the group of antheridia 

 through the terminal cell, which is destroyed during the process. The development of the receptacle 

 is almost exactly that of Rickid, except that the cell (o) of fig. 3, Plate XXXIV, is not divided 

 longitudinally, but as a result of transverse divisions, develops, like cell (x) of fig. 4, to form the 

 posterior series of the receptacle, the median series of Richia not developing at all. 



The genus has an especial interest as suggesting that the simple antheridium may possibly have 

 arisen from the compound, rather than that the reverse has taken place, and as indicating the method 

 by which this may have been affected. Yet it should not be regarded as in the least proving that the 

 evolution of the antheridium in the family has not in general been from the simple to the compound 

 type. 



Distichomyces Leptochiri Thaxter. Plate LXXI, figs. 1-6. 

 Proc. Am. Acad. Arts and Sci., Vol. XLI, p. 308. July, 1905. 



Slender and considerably elongated, or sometimes short and stout: the primary axis consisting of 

 from twelve to thirty cells, more or less, above the subbasal cell of the receptacle, somewhat proliferous 

 distally beyond the base of the primary appendage, the small cells thus formed, one or two of them ap- 

 pendiculate, extending to the free tip of the perithecium; the perithecial axis consisting of from six to 

 twenty-six cells, more or less; the perithecium slightly broader, but not distinguished from the axis, 

 wholly united on its inner side to the primary axis, more or less strongly curved outward to its blunt sub- 

 truncate free tip. Appendages as in Peyritschiella, hyaline, rather slender, very variably developed, 

 borne on a small triangular cell, separated distally and externally from the cells of the axis; sometimes 

 numerous, often few and scattered, or almost wanting except distally, where all the cells of the primary 

 axis are usually appendiculate. Antheridial branches borne like the sterile branches, irregular in posi- 

 tion and number, sometimes even absent, usually confined to the lower half of the axis, more often near 

 the base, consisting of a short stalk-cell bearing terminally a compact erect group of flask-shaped an- 

 theridia, usually four or five in number, their short broad necks at first closely approximated or 

 coherent, divergent only after full maturity. Perithecium 50-55 X 15-20 fi. Longer sterile appendages 

 75 X 6 /«. Antheridial branch, including antheridia, 18 [x. Total length, longer 475 X 10 /z, shorter 

 and stouter 125 X 36 /j.. Secondary perithecia may develop from cells of either axis if the primary 

 perithecium does not develop or is destroyed. 



On the head, antennae and under surface of Leptochirus sp., Java; Rouyer, No. 1403. 



This species shows very considerable variation in its general habit and in the distribution of its 

 appendages and antheridia, as is indicated by the accompanying figures. As usually happens, individ- 

 uals which occur on the legs, or in other exposed positions, are commonly short and stout; while those 

 on the thorax or abdomen are characteristically elongate. On account of its small size and pale color 

 it is detected with great difficulty. 



DICHOMYCES Thaxter. 

 This genus, of which only three representatives were included in my Monograph, has proved one 

 of the larger genera of the family, including over twenty species of varied habit, although the general 

 type is remarkably constant. The species appear to be very sensitive to unfavorable conditions, and 

 one can usually be sure of finding typically developed individuals only on the body or elytra of the host, 

 those developed on the appendages being, in general, malformed and continually reverting to the Pey- 

 n/sc/ftW/a-condition; losing the bilateral symmetry of the receptacle, which is constant in well developed 

 individuals of all species, and possessing but a single antheridium. Such a form of D. inaequalis was 

 formerly described as a new species of Peyritschiella, P. nigrescens, but is undoubtedly a reversion of 

 this nature. Since Dichomyces must be considered merely as an elaboration of Peyritschiella, this re- 



