MONOGRAPH OF THE LABOULBENIACE^E. 



309 



of two cells, a lower (cell II) and an upper (cell IV), the inner upper portion of which is 

 separated as a third cell (cell V, which is in reality made up of two cells placed side hy side), 

 the former consisting of a lower (cell VI) and an upper (cell VII) obliquely superposed. 

 Appendages arising from a blackened insertion cell above cells IV and V (exceptionally from a 

 variable number of subdivisions of these cells, in which case the black insertion cell is wanting). 

 Perithecium solitary, compressed, asymmetrical or nearly symmetrical, rarely appcndiculatc, 

 sessile' or stalked, having four wall-cells in each longitudinal row. Appendages sometimes 

 numerous, but typically consisting of two basal cells, from the outer of which arises one, from 

 the inner two branches or series of branches, the inner fertile bearing the flask-shaped anthcridia, 

 singly or more or less irregularly grouped. Ascogcnic cells two, lateral. Asci four-spored. 

 Spores once septate. Trichogyne filamentous, simple or branched. 



Owing to the occurrence of several exceptional modifications in the structure of certain 

 members of this genus, it is very difficult to characterize it briefly and concisely ; and owing to 

 the fact that it contains nearly half of all the members of the family, its variations are, as might 

 be expected, very considerable. The more striking departures from what may be considered the 

 type form, are illustrated by the following species : L. Gyrinidarum, L. Guerinii, L. Orectoyyri, 

 L. Oberthuri, L. variabilis, L. brachiata, L. fascicidata, and to a less extent by L. proliferans 

 (Plates XXI and XXII), in all of which the usual black insertion cell is absent or modified, 

 while cells IV and V have undergone division above into a series of cells differently arranged in 

 different cases, all of which may give rise to appendages. A further abnormal septation of these 

 two cells of a somewhat different character is seen in L. Clivince (Plate XXI, figs. 16-17), a 

 species otherwise peculiar for the coalescence of its appendages at the base. Typically the 

 black insertion cell bears above it two cells, an outer forming the base of a single simple or 

 branched sterile appendage ; the inner giving rise on either side to a branch which is fertile and 

 may be variously divided. The complications of this simple type are, however, numerous and 

 often very striking, resulting either from the sub-division of one or of both of these basal cells, 

 and the production from them of more numerous branches ; or from a combination of both these 

 modifications. Such variations are well illustrated by species like L. Brachini, L. luxurians, L. 

 minima, L. Zanzibar ina or L. Galeritoe. 



A second departure from the type form is illustrated by such species as L. Kunlceli, L. longi- 

 collis, L. Galcritce and their allies (Plates XVIII and XIX), in which the lower cells in each of 

 the four series of wall-cells of the perithecium become greatly elongated, forming a well defined 

 stalk on which the latter appears to be borne. 



The perithecium is also subject to considerable variation in form, especially as regards the 

 modifications of its lip-cells. In two cases the latter are appendiculate (JL. Gyrinidarum and 

 L. cornuta); while in others they are curiously expanded (L. umbonata, L. texana, etc.) or 

 irregular. The four rows of wall-cells may sometimes show a distinct spiral twist, as in L. arcu- 

 ata, L. decipiens (Plates XVIII and XX) and a few other forms, and are composed of four cells 

 each ; although, except in younger specimens, the usual blackening below the pore obscures the 

 upper septa. 



The trichogyne, although it is sometimes merely a simple, sparingly septate filament, is more 

 commonly, often very copiously branched, the receptive tips being either straight (Plate II, fig. 3), 

 or in many instances spirally twisted (Plate XXI, fig. 15). The antheridia are generally very 



