cis | PROCEEDINGS OF THE NATIONAL MUSEUM. A491 
i 
very slightly faleate, united to a considerable distance from the base, 
acute to subacute. Mid nerve slender but distinct, splitting into 
branches at the summit. Lateral nerves single. The ultimate pinnae, 
in ascending toward the summit of the frond, pass through pinne with 
ovate acute lobes into those with serrate toothing, and finally into en- 
_ tire pinnules. 
Sori, seen only on serrately toothed pmne, are very large, single in 
each segment or tooth, globose or subreniform in shape, attached to a 
_ ¢lub-shaped receptacle that is borne on the summit of a basal lateral 
; nerve, which is directed obliquely upwards. They occupy the greater 
portion of the upper half of each segment or tooth. Nerves of the fer- 
- tile pinne in a bundle in each segment or tooth, and splitting up flabel- 
~ lately into branches. 
_ This fern, as shown in the fructification, isa new species. There are 
_ numerous good imprints of it, so that its character can be made out 
pretty well. It occurs in the same yellowish gray sandy shale that car- 
ries Aspidium montanense. Some of the sterile forms approach so near 
tosome of Aspidium montanense that they can with difficulty be dis- 
_ tinguished. The fructification, however, is entirely different. The 
_ pinnules and segments of this fern have more of the aspect of Clado- 
 phlebis than any form of A. montanense. They are more acute, more 
inclined forward, and have a broader base than those of the last-named 
~ fossil. 
‘Pi. uxxxim, Fig. 6, shows a fragment of a compound pinna from the 
_ lower part of the frond, and Fig. 6*a portion of the same enlarged. Fig. 
4 gives the ovately eid serrately toothed pinne or pinnules from the 
_ upper part of the frond. Fig. 5 gives the termination of a compound 
pinna. Pl. Lxxxtv, Fig. 3, gives a portion of a fertile compound pinna, 
and Fig. 3* a fertile fragment enlarged to show sori and nerves. 
_ Different portions of this fern, if taken alone, could be with difficulty 
_ distinguished from several Potomac plants. Some of the serrate toothed 
; forms are exactly like some of the forms of- Pecopteris virginiensis; 
_ Some of the ovately lobed pinne much resemble some of the forms of 
_ Aspidium heterophyllum. In size and structure the sori are like those 
; of Polypodium fadyenioides of the Potomac strata. The mode of at- 
; tachment of the sori and the nervation of the fructified forms of Poly- 
podium dentatum of the Potomac resemble those features in this fern, 
but the sori of the Potomac plant are smaller and of different shape. 
Aspidium angustipinnatum Font., var. montanense, var. nov. 
Pl; LEXI, ims: ela: 
This fern is represented by six imprints, some of which are well pre- 
served and well characterized. Although somewhat different, it agrees 
in all essentials so, well with Aspidium angustipinnatum Font., of the 
Virginia formation, that I do not think that they should be considered 
