Igto0] KERN—PERIDIAL CELLS IN ROESTELIAE 451 
and are directed downward and outward and extend obliquely on to 
the side walls. In some species the ridges are of uniform width 
(figs. 5, 10, 14), in others they become somewhat broader toward the 
outer side (fig. 2). In some species the long ridgelike markings 
are closely and rather evenly arranged (figs. 3, 10), while in some they 
are rather sparsely set with separate and shorter, sometimes roundish 
papillae in the intervening spaces (jigs. 2, 5, 8). Nos. 6, 7,9, 15, and 
165 have verrucosely roughened cells. The warts vary from roundish 
or slightly irregular (figs. 6, 7, 15, 16) to very irregularly branched 
forms (fig. g), and are arranged without apparent order. They 
are usually more sparse toward the outer portion of the side walls. 
The verrucose character is pronounced in only one form, G. Nelsoni 
Arth., which consequently occupies this class by itself (fig. 13). 
PURDUE UNIVERSITY 
LAFAYETTE, INDIANA 
EXPLANATION OF PLATES XXI AND XXII 
The drawings were outlined with the aid of a camera lucida at a uniform 
magnification of 625 diameters, and were reduced about one-fifth in reproduction. 
In every case the end which is uppermost on the plate is the upper end of the 
cell, or, in other words, the end which is toward the apex of the peridium. 
all figures except 17 and 172 the inner wall can readily be distinguished by its 
relatively greater thickness. 
PLATE XXI 
Fic. 1.—G. Bermudianum Farl.: a, side view; 6, face view. 
Fic. 2.—G. Juniperi-virginianae Schw. (R. pyrata [Schw.] Thaxt.). 
Fic. 3.—G. florijorme Thaxt. 
Fic. 4.—G. Senex Farl. 
Fic. 5.—G. Betheli K 
Fic. 6.—G. dascticierms (Jacq.) DC. 
Fic. 7.—R. transjormans Ellis. 
Fic. 8.—G. juniperinum L. (R. pennicillata [Pers.] Fries.). 
FIG. 9.—G. germinale (Schw.) Kern (R. aurantiaca Peck). 
PLATE XXII 
Fic. 10.—G. nidus-avis Thaxt. 
Fic. 11.—R, hyalina Cooke: a, side view, the thick wall is the outer wall 
here; 6, face view. 
5 These numbers also correspond to the figure numbers on the plates. 
