THAXTER. — 



MONOGRAPH OF THE LABOULBENIACELE. 



229 



seems to be entirely so as far as the cell relations in development are concerned, a single instance has 

 been found among the recently discovered genera in which the antheridial cells, although they almost 

 certainly originate as in typical compound antheridia, become ultimately free in a compact group, each 

 discharging independently; the cell below which they were formed and through which they would nor- 

 mally discharge by means of a common opening, being sloughed off and destroyed early in their devel- 

 opment. The genus Distichomyces in which the conditions just described appear to exist, is so closely 

 allied to Rickia that it might almost be included in it, yet in RicJcia highly specialized compound antheridia 

 arc present. Moreover the close relationship of both these genera to the group of genera assembled 

 about Peyritschiella, and possessing typical compound antheridia, cannot for a moment be questioned. 

 If therefore, one makes an absolute distinction based on the characters of the mature antheridium, as has 

 been done in the tentative key to the genera herewith appended, the genus Distichomyces would naturally 

 be sought among the "LaboulbeniaeeaV where it certainly does not belong. 



The type of the simple antheridium is in general a very constant one, although there may be a rather 

 wide variation in the minor characters, the form of the venter, length and curvature of the neck, and 

 the relative proportions of its two parts. The relations of the simple antheridia to one another, when 

 they occur in groups, was formerly emphasized as a matter of importance in distinguishing certain genera 

 and species, the serial arrangement being the most distinctive. The genus Stigmatomyces, to which 

 many species have recently been added, illustrates this condition very clearly, although in this highly 

 differentiated appendage, the antheridial cells are not always, or even usually, as was formerly stated, 

 superposed in a single row, as is the case in S. virescens, or S. purpureas, Plate XLVI, fig. 36; but a series 

 of sympodia is formed, each antheridial branchlet separating a basal cell, which in turn grows out directly 

 to form a second antheridium, so that the series is double at least in the lower portion of the appendage, 

 Plate XLIX, fig. 13. The lowest groups may even produce more than two antheridial cells, as in S. 

 constrictus, Plate XLVI, figs. 1-2. This last condition tends to break down the distinction based on 

 antheridial series between this genus and Arthrorhynclvus, Plate XL VIII, in one species of which, fig. 3, 

 the arrangement is very similar. A single type in which the antheridia are strictly intercalary, like those 

 of Corethromyces, has been added in the genus Symplcctromyces, Plate L, figs. 14—10, but this relation ap- 

 pears to be a rare one. The number of antheridial cells in such associations appears to be more or less 

 definite in certain cases. In a majority of the species of Stigmatomyces, for example, this character seems 

 to be one of the most useful in distinguishing species, while in Teratomyces, on the other hand, in which 

 the antheridial branch is also a monopodium, there is absolute irregularity in this respect. A new and 

 very individual type of appendage somewhat similar to that of Stigmatomyces is seen in Acompsomyces, 

 and another less well defined in Acallomyccs; these appendages being in general simpler and tending to 

 break down any abrupt line of demarcation between types of appendages with serially arranged antheri- 

 dial cells, and those in which the latter are irregularly placed. A few instances occur in which the group- 

 ing of the antheridial cells is of specific, though not of generic value, a condition best illustrated, in the 

 genus Laboulbenia, by such species as L. Oezenw, Plate LXIII, fig. 11, or L. variabilis. 



The transition between simple, but distinctly differentiated, antheridial cells, and the undiffer- 

 entiated segments of an appendage or its branches, which may serve a similar purpose, has already 

 been referred to, and is illustrated most clearly by Coreomyces, Plate LXXI, fig. 13. These segments, 

 although they discharge their contents in a similar fashion, are evidently variable in size and form, 



