302 



THAXTER. — MONOGRAPH OF THE LABOULBENIACE^E. 



to a terminal cell and the different species may be in general divided in two groups, one in which the 

 spinose cell is terminal at maturity as in figs. 1, 7, 3G, 41 etc., Plate XLVI; and a second class in which, 

 through a process of secondary proliferation more or less pronounced, the spinose cell becomes inter- 

 calary, and the number of cells forming the axis of the appendage correspondingly increased in number, 

 as in fig. 29. In this class also two types may be distinguished namely that in which all the cells of the 

 axis, at least above the basal cell, bear fertile antheridia, whether they be primary or secondary, as in the 

 figure last cited, and those in which the accessory cells of the axis are partly or wholly sterile, producing 

 no antheridia or only sterile ones, as in figs. 7 and 13, Plate XPVII. 



In regard to the development, arrangement and number of the antheridia on the appendage, there is 

 a good deal of variation in different cases, but these characters appear to be more or less definitely fixed 

 in individual species, so that the appendage characters are often the only reliable ones. The simplest 

 type of arrangement is that seen in S. purpureus previously cited, in which each cell of the axis having 

 cut off a single antheridium, the latter form a series of members superposed in a single row. This type, 

 however, is rarely met with, and in the great majority of cases a more or less complete double row is 

 formed. This condition usually results from the fact that from some or all of the cells which compose 

 the primary axis, a second cell is cut off which corresponds to the single antheridium of the simpler type 

 and like it is morphologically a lateral branch. This branch then divides in two superposed cells, the 

 terminal one being converted directly to an antheridium. The basal cell in turn may then grow out 

 sidewise and form a second antheridium on which the first appears to be superposed, or may itself become 

 divided to an upper and lower cell each of which is transformed to an antheridium, as appears to be the 

 case in S. Elachiptcra. The antheridia formed in this manner becoming somewhat divergent as they 

 mature, thus come to be more or less regularly biseriate and alternate. These antheridial sympodia 

 from the main appendage correspond in all respects to the corresponding structures of Rhadinomyces, 

 in which the antheridia arise successively in a similar fashion (Monograph, Plate IX, fig. 23), although 

 they are quite free and usually more than two are superposed. 



In describing the species it has been found convenient to distinguish three regions in the perithecium 

 although they are not well marked in all cases. These are the venter, the more or less swollen ascigerous 

 basal part, the neck often abruptly distinguished and elongate above it and lastly the tip which is com- 

 monly distinguished from the neck by a more or less well defined elevation. A typical instance of this 

 separation into three regions is seen in the perithecium of figs. 12 and 16, Plate XLIX. In several species 

 the venter is marked by granulations or transverse lines as in the figures last cited, but this is often indis- 

 tinct without a high magnification. The hosts of the members of this genus are mostly small flies many 

 of which, as their names suggest, live near water or in moist places, while others may be swept with a 

 net from various flowers or over grass etc., in somewhat dryer situations. It will be remembered that 

 S. virescens occurs on a widely different host, Chilocoru.s, one of the "lady beetles," and I have one other 

 species as yet undescribed which occurs in South America on another order of Coleoptera. It may be 

 mentioned here that, although the species almost all grow on soft bodied hosts, no indication has been seen 

 of any penetration of the integument such as is suggested by the figures of Peyritsch, and the foot is of the 

 usual type, though often small. 



Stigmatomyces purpureus Thaxter. Plate XLVI, figs. 30-36. 

 Proc. Am. Acad. Arts and Sci., Vol. XXXVI, p. 404. March, 1901. 



Becoming wholly suffused with purple. Venter of the perithecium inflated toward the base, tapering 

 distally; the four wall-cells separated by a corresponding number of prominent longitudinal ridges, 

 rounded in section, which run spirally, making in well-developed individuals a whole half turn about the 

 venter, and becoming sometimes lobulated through the presence of successive constrictions and enlarge- 

 ments; neck not abruptly distinguished, except by the abrupt elevations which form the terminations 

 of the longitudinal ridges of the venter, rather slender, an abrupt posterior subterminal elevation preceded 



