292 MKSOZOIC FLORAS OF FXITKI) STATFS. 



The norvalioii varies willi the pinnules. It is very distinct and 

 sharply defined. In this respect it siupasses that of the forms of this 

 species found in the Potomac formation of \'ir<2;inia. .\s stated, the 

 loniT crenate pinnules were not seen attached, hut in the normal jiin- 

 nules with entire margins the midnerve leaves the rachis at an acute 

 angle and enters the pinnule near its lower basal margin, so as to divide 

 the lamina into une(iual parts. It becomes vei'v gradually attenuated, 

 and, as is the case with C'ladophlebis, splits u[) at its end into several 

 branches. The lateral nerves of the normal pinnules, although dis- 

 tinct, are I'ather slender. They go otT very ol)li{{uely from the midrib 

 and curve outward toward the margin of the pinnules. They fork 

 near their insertion, and each liranch forks again at about the middle 

 of the lamina, while the branches continue nearly parallel to one another 

 until they meet the margin. This nervation reminds one f)f that of 

 the small-pinnuled neuropterids of the Paleozoic. The basal nerve 

 btmdle on each side of the midnerve is inserted, not on the midiierve, 

 but at the point of its attachment to the rachis of the pinna. 



The lateral nerves of the long crenate and of the lol)ed pimniles 

 form nerve Ijundles that go ofT obliquely from a common point of inser- 

 tion and are composed of several branches, which in turn split up into 

 others, the whole group diverging flabellately and curving away from 

 the midrib to meet the margin at a large angle. These nerves are rather 

 coarse. The nerve bundles fill the lobes and crenate incisions. All 

 the lateral nerves, in every part of the plant, are noteworthy for the 

 length of the branches into which they split up. In the pimniles toward 

 the ends of the pinnte and in the upper part of the frond the lateral 

 nerves are forked only once. 



This fine fern is one of the most abundant fossils in the (Jeyser 

 group of strata and it is the best preserved. A large number of impres- 

 sions of good size and belonging to different portions of the plant have 

 been found. In these we find some features different from the character 

 of C.falcaia, as made out from the fossils of the Potomac beds of ^'irginia." 



It may be questioned whether or not these forms show enough 

 difference from the species of the Virginia Potomac to justify their 



"Potomac Flora (Mi)iio<;r. V. S. Gi'ol. Surv., Vol. XV), pp. 72, 73, pi. iv, fig. 8; pi. v, figs. 1-6; pl.vi 

 fig. 7; pi. vii, figs. 1, 2. 



