BENEDICT: GENERA OF THE FERN TRIBE VITTARIEAE 161 
species of the other genera of the tribe, all five are here shown 
together in one plate (PLATE 3). The species may be compared 
as follows: 
Leaf trace undivided throughout, paraphyses distinctly capitate. 
Leaves 5-10 cm. long (Mauritius). M. graminea. 
Leaves not more than 3 cm. long (Borneo, Philippine Is.). M. dareicarpa. 
Leaf trace with 1-2 or rarely 3 divisions, paraphyses not capitate. 
Leaves hairlike; twisted, with sporangia in I-3 separated grooves 
in a line along the leaf (Philippine Is.). M. trichoidea. 
Leaves flat, more or less falcate, the sporangia in a single or in 
© parallel grooves. 
Leaves about 2.5 cm. long, with only one areola and soral 
line (New Hebrides). M. subfalcata. 
Leaves much longer, up to 25 cm. long, often with two areolae 
and soral grooves (Oceanica and Malaysia). M. paradoxa. 
The structure of the leaves and their venation is sufficiently 
well shown so that little description is needed. In M. paradoxa 
the majority of the leaves show only a single areola and sporangial 
line, but the type with two, as figured, is not unusual. In M. 
trichoidea the section shows that the leaf trace may divide, at 
least along some of the soral grooves, but the material does not 
soak up well and it was not determined whether this is true in all 
cases. The shape of the sporangial groove appears from the gross 
study of a number of leaves to vary somewhat, being often more 
nearly equal-lipped. M. graminea and M. dareicarpa are alike 
in the type of soral groove. There is possibly a slight difference 
in the shape of the paraphyses. This, together with the difference 
in size and the wide separation in range, makes adequate specific 
separation. M. subfalcata is similarly related to M. paradoxa, 
and is not so well separated in distribution, but from the material 
studied, and this included a considerable series of M. paradoxa, 
their separation appears justified. 
From the standpoint of species differentiation, Monogramma 
is interesting as showing the possibilities of variation in the very 
simple structure involved. The genus stands at the bottom of 
the scale in comparison with other vascular plants, the mature 
leaf being simpler in structure than the stage which appears in 
the first leaf in other ferns. The differentiation is, as noted, 
usually coupled with differences in the distribution, but at least 
three of the species may occur in the same general region. 
