DESGIUPTION OF TllK SPECIES. 163 



upper margin ; tliis varies witli tlie jjosition of tlie lobes on tlie pinna' and 

 the frond ; on tlie lower lobes and pinnK' it is broadly triangular, rather 

 deeply cut, and directed outwards ; in tlic ixpper pinnaj and lobes it is 

 minute, shallow, and spinous; in the upper portions of the frond the lobes 

 end in or graduate into spine-like teeth, Avhicli are sometimes much prolonged 

 and quite slender, these teeth directed forwards or outwards are single or 

 double. The reduced ultimate pinnjTo or pinnules end variously, either in 

 two or more acute teeth or in an ovate-denticulate lobe ; midnerve of the 

 ultimate pinna' or pinnules strong towards the base, rapidly much atten- 

 uated higlier, and at the sunnnit dissolving into branches ; nerves of each 

 lobe or pinnule of tlie basal portions of the lower pinnoj or pinnules 

 composed of a nerve-bundle which goes off very obliquely from the 

 rachis below the base of the lobe or pinnule, curving strongly outwards, 

 forking near the base, with each branch forking deeply once or twice again. 

 Towards the summit of the ultimate pinnie the lateral nerves become very 

 oblique, do not curve so suddenly and strongly outwards, but continue for 

 a long distance, more or less in tlie direction of the axis of the pinna, are 

 forked several times with long branches, forming indeed the branches into 

 which the midnerve splits up. In the upper toothed pinna the midnerve 

 (see PI. LXTV, Figs. 1", 1'') continues only a little more tlian one-third of 

 the length of the pinna. It is split up into very obliquely placed, slightly 

 diverging, and verj' deeply forking branches, which fork once or twice, and 

 have very long, slender, idtimate ])ranches. The lateral nerves from the 

 lower portions of these pinna', go off very obliquely, fork once or twice, 

 and have very long, slender, ultimate branches. 



Locality r Fredericksburg ; rather common. 



The specimens obtained of this plant show that it must have attained 

 a very large size. The fragment figured in PI. LXIV, Fig. 1, is probabh' 

 a portion of a compound pinna of large dimensions. The si)ecimen given 

 in PI. LXV, Fig. 4, which is a portion of probably a })enultimate pinna, 

 shows that these must have been in some cases very long. The epidermis 

 over the pinnules and rachises of PI. LXIV, Fig. 1, was so thick and dur- 

 able, that it could be peeled off like paper. Plate LXIV, Fig. 3, seems to 

 show a fragment of a penultimate piima, forming the lower portion of one 



