BENEDICT: GENERA OF THE FERN TRIBE VITTARIEAE 183 
without speculation as to their significance. But because of the 
facts presented, three questions stand out as of especial interest. 
First, what are the probable relationships of the Vittarieae? 
Second, what is the significance of the simple type in M onogramma? 
Third, what evidence as to the theory of recapitulation is offered 
by the parallel venation series seen in the mature sporophytes 
and in the growth stages of the more advanced genera? 
1. RELATIONSHIPS OF THE VITTARIEAE 
Before considering the possible relationships of the tribe, it 
should be emphasized that only those characters in which all the 
genera agree, or which appear regularly in the more primitive 
genera, may be used for comparison. This fact may seem too 
self-evident to need stating, but its disregard has led to some 
erroneous comparisons, of which I have contributed one in com- 
paring Antrophyum with Loxogramma Presl of the tribe Poly- 
podieae.* 
The characters in which all the genera agree are found in the 
arrangement of the sporangia, in the type of rootstock scales, 
and in the presence of the differentiated epidermal idioblasts. 
Goebel found that the prothallia of a number of species in Vittaria, 
Hecistopteris, and Monogramma are of a peculiar type characteristic 
of the tribe. E. G. Britton and A. Taylor added Vittaria lineata 
to the list of species known to show the specialized type of pro- 
thallium, and I have found the same specialized sort in Polytaenium 
lanceolatum and in Vittaria (Radiovittaria) remota, two groups for 
which the gametophyte has not before been noted. Now there 
remains only to show that this type is characteristic also of Antro- 
phyum,Ananthacorus, and Anetium, in order to demonstrate beyond 
a doubt that it is a tribal character. One other character may be 
included here as characteristic of the Vittarieae generally, viz., the 
uniformly parenchymatous structure in all parts except the vascular 
bundles. 
Of these characters, the first two mentioned offer the best 
basis of comparison with other fern tribes, and furthermore both 
seem to indicate similar relationships. The resemblance in the 
sporangial arrangement to that which obtains in the Pteridieae 
* Bull. Torrey Club 34: 445. 19 O 1907. 
