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 conflupnt, 

 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 pinnge, pinnae 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 interesting species are: 

 Cyathea Noclcii, already briefly described (pi. 8) ; C. Brooksii, 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 



