482 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
from Eucyathea was given the name Eatoniopteris, in honor of the 
late Prof. Daniel Cady Eaton, of Yale University. The numerous 
species of this group are distinguished by having the indusium 
globose and wholly inclosing the sporangia, until at maturity these 
distend the indusium beyond the bursting point; whereupon, having 
no sutures or definite lines of cleavage, it ruptures irregularly, its 
ragged divisions being thrust outward. A species having this type 
of indusium (Cyathea Brunei, of Costa Rica and Panama) is illus- 
trated in plate 9, figures C and D. The first of these shows the firm, 
white, unbroken indusia in a condition approaching maturity, and the 
midribs of the segments still clothed with dark slender scales. In 
figure D is shown an older state of the same species, in which it will 
be noticed that the sori have burst and appear more or less confluent, 
and that the indusia, though irregularly broken, have partially resumed 
their original position. In this and several other species having thick 
or firm indusia it will be found that the divisions commonly persist or, 
at least, tend to disappear only with age, sometimes spreading apart 
hardly more than enough to allow the spores to escape freely, then 
drawing in nearly to their original form and appearing valvelike. But 
in many other species the indusia are thin or even of such extreme 
delicacy that they appear merely as a slight, translucent membranous 
film. In these the indusium is too delicate to withstand the explo- 
sive hygroscopic action of the sporangia, so that after the spores have 
been shed there will be found only traces of the broken indusium, a 
few half-detached fragments appearing among the mass of confluent 
sporangia, or sometimes only a small basal portion persisting in the 
form of a thin flattish scale, which may be wholly concealed by the 
sporangia, at the base of the receptacle. During the process of spore 
shedding, or it may be merely with age, the scaly covering of the mid- 
ribs of the underside of the segments often will either have disap- 
peared or have become so mixed with broken sporangia, spores, and 
fragments of the indusia as to be almost indistinguishable. On this 
account it is essential in collecting material to secure, in addition to 
fully mature pinne, pinne from other fronds in which the sori are so 
young that they will not burst in drying but will retain their original 
form. The very general failure of collectors to observe this precau- 
tion is responsible for much of the confusion which will always result 
from the study of carelessly selected and imperfectly prepared her- 
barium material in so critical a group. 
Of the section Eucyathea, some of the more e interesting species are: 
Cyathea Nockii, already briefly described (pl. 8); C. Brooksw, a Cuban 
species with a short, horizontal, mostly subterranean rhizome and 
several long-stalked bipinnate fronds about 4 feet high; C. minor 
and C. pubescens, the former with a very slender, clean trunk, the 
