896 KLOKAL ZOXES OF THE POTTS VILLE FORMATION". 



provided. l)t't\vet'n tlir ultiiiuite pinna', with polyuiorphous broad, .short 

 pinnules. 



Pinnules of the ultimate pinine linear-, or sliixhtly triangular-linear- 

 subfaleate, usually short, four to six times as long as broad, with narrow 

 cordate or slightly squarrose base, tapering upward toward the obtuse 

 or obtusely acute apex, and usually turned upward with a uniform 

 curve throughout the whole length, though often nearh' straight; tiie 

 rachial pinnules triangular, triangular-ovate, cordate, or even cordo- 

 reniforni, and very small; lamina a little thick, depressed in a narrow, 

 rather shallow furrow along the median line, slightly convex ventrally, 

 especiall}^ at the margin. 



Nervation sharply distinct, ventrally depressed, dorsally in relief; 

 median nerve not very strong, but distinct and traceable to very near 

 the apex; nervilles originating at a moderately open angle, a little 

 distant, forking at a slightly open angle near the base, and similarly 

 once or twice again, according to the size of the pinnule, in curving 

 toward the margin, which the}^ meet obliquely, except in the lower 

 part of the pinnule, counting about 30 to 38 per centimeter. 



Although the pinnules of this species occur in great abundance on 

 the surface of the shales, no large segments of pinnae have been found. 

 Nevertheless, the presence of the small and somewhat polymorphous 

 pinnules, corresponding to those from the rachis in the preceding 

 species, as well as the phases and similar characters of the large pin- 

 nules, strongly indicates a development of the pinna? in the same general 

 manner as in Neuropteris gigantea^ to which it is undoubtedly closely 

 related. 



The most noticeable features of the pinnules are their slenderness, 

 the crescentic curvature, the squarrose-cordate base, the distinct mid- 

 rib, and the slightly distant nerves, which fork a little widely, although 

 the divisions may at once assume a nearly parallel direction. 



The piniudes of N'. hmata are more slender than those of y. gigan- 

 tea, and proportionately less acute, the curvature, when present, being 

 generally more uniformly distributed, slightly crescentic, through 

 the whole length instead of being expressed as an upward turn n 'ar 

 the apex. Often, however, they are but slightly curved or nearly' 

 straight. The midrib is much stronger and more persistent even 

 than in X. ZeUlarl Pot.,' it being clearly traceable, though thin, very 

 nearly to the apex. The angle of division of the nerves, as noted 

 above, appears greater than in the last species, and is certainly much 

 greater, while the nerves are less oblique, than in N. glganfea var. 

 clavata. Some of the small roundish rachial piiuiules seem, when 

 detached, to be not separable from similar small basal pinnuUvs in 

 some other species of Nenropterla. But the average piimules may be 



i.Tnhrb. fl. k. Pr. Oi-ol, T,!iiKlcsiinst n. Bcrgakad., Vol. XU, p. 22, pis. li-iv, text fig. 1-4. 



