BENEDICT: GENERA OF THE FERN TRIBE VITTARIEAE 167 
species for identification but which need not be described here. 
They consist, as noted in the tribal descriptions, of enlarged, 
usually brown or yellow end cells, borne on single or branching 
multicellular pedicels and associated with the sporangia. 
The sporangia are always borne along the outer interlocking 
portions of the veinlets as continuous lines along the greater part 
of the lamina (PLATE 2, FIG. 4, 5). With perhaps not more than 
two exceptions, the sporangial line is always in a groove or depres- 
sion of greater or less extent. FIGURE 12 of PLATE 5 shows a 
very slightly depressed groove. FicurEs 6, 8, 9, and 21 of the 
same plate show some of the deeply grooved species and the 
variety of ways in which the groove may be disposed. According 
to the development of the grooves, the species have sometimes 
been described as possessing indusia or otherwise. FIGURES 6 and 
12, respectively, illustrate these two types. The use of this term 
is hardly advisable as there is no real differentiation of one lip as a 
distinct indusium. This is equally true of Monogramma (PLATE 
3, FIG. 2, 7, 9, 14, 15, 19), as also of all the species in which the re- 
ceptacle is sunk in a groove. 
The various types of sporangial groove have been thoroughly 
studied and figured by Luerssen. (Filices Graeffeanae, in Schenk 
and Luerssen, Mitt. Gesammt. Bot. 1: 57. pl. I1, 12. 1871.) 
This, by the way, is the only feature of the Vittarieae that has 
been adequately studied through any considerable number of 
species. ; 
It has already been noted that the venation of the simplest 
species of Vittaria is essentially the same as that of Monogramma 
paradoxa, and that the separation in this direction must depend 
on the separate sporangial lines. With respect to the more 
advanced genera, the characters of the venation furnish the best 
distinction. As regards the soriation, certain species of the more 
advanced genera appear sometimes like Vittaria. 
B. PLURISERIATE GENERA 
The remaining genera of the tribe all show a more advanced 
type of venation than that of Vittaria. If the latter with its 
two separate rows of areolae may be called ‘“‘biseriate,’’ the more 
complex type may well be named “pluriseriate,” since there are 
