Slender Cliff-Brake 95 
Cryptogramma Steller (S. G. Gmel). Prant, Engler’s Bot. Jahrb. 3: 413. 
1882. 
Pteris Stelleri. S. G. Gmel., Nov. Comm. Acad. Sci. Petrop. 12: 5109. 
IAL A is tte HOLS 
Pella Stelleri. Watt, Can. Nat. : 3158. 1867. 
Pteris gracilis. Michaux, Fl. Bor. Am. 2: 262. 1803. 
Pellea gracilis. Hooker, Sp. Fil. 2: 138. Pl. CXXXIII. B. 1858. 
I HAVE not been able to obtain leaves of Cryptogramma Stelleri 
portraying earlier stages of leaf-development than the leaves 
figured in Pl. XXI, but from the figures the general develop- 
ment of the form and venation of the leaf can be seen. 
It will be noted that the venation is pinnate, and that when 
new segments form on the leaf, many duplicate to a certain 
extent the earlier segments. For instance, compare Figs. ra, 
2a, 4 a, 64a, 8a (Pl. XXI), and 2a (PI. XXII). 
It will also be noted that the fertile leaf figured has no ter- 
tiary segments (Pl. XXII, Fig. 1). Tertiary segments are often 
lacking in the mature leaves. 
The incision by means of which the first basal primary 
branch of the midvein of any one of the leaf’s segments is set 
apart to constitute the midvein of a new segment sometimes 
occurs while the midvein of the existing segment is little de- 
veloped, and before other incisions occur in this segment: which 
often gives the subdividing segment the appearance of being cut 
vertically into two nearly equal parts. 
The midveins in newly formed segments are sometimes not 
developed beyond two simple primary branches. In segments 
in later stages of development they are conspicuously developed. 
In the transformation of the sterile leaf into a sporophyll, 
the leaf’s ‘petiole lengthens, and the leaf-blade’s margin recedes 
slightly and folds backward on the sides of the leaf’s segments 
