DESCIUI'TION OF THE Sl'KCIES. 137 



stance leatliery aiul thick ; nerves vei'v strong, causing the leatiets some- 

 times to look as if they were corded. In the crenate pinnules (Fig. I'') the 

 nerves consist of a midnerve which splits up towards the summit and sends 

 off at base two nerve-bundles ; these diverge flabellately into the teeth, with 

 the branches simple and forked; higher the lateral nerves fork deepl\-, 

 with the upper branch forking again; the entire pinnules (Fig. P) have 

 branches diverging alternately from a midnerve, curving outward and once 

 or twice forked. 



Locality : Fredericksburg ; rather rare. 



This })lant belongs to the Sphciiopteris Gu'ppcrti type. It seems to be 

 a well-characterized new species of a strongly defined Wealden type. 



TlIYRSDPTEKIS VARIANS, Sp. UOV. 

 ri;ito UI, rigs. 2-4; Tlate LIII, Figs. 1-3; Plato LIV, Fif?. 10; Plate LVII, Fig.-.'. 



. P^'rond tripinnate or quadripinnate, large and spreading; leaf-substance 

 thick and leatliery ; rachises of the penultimate piniue often partially or 

 fully winged ; ultimate pinnje varying in size and shape with their posi- 

 tion on the frond, tending to pass in ascending towards the ends of the 

 penultimate pinnrc rapidly through lobed into entire pinnules. Principal 

 rachis generally stout and prominent, often flexuous; ultimate pinna' on 

 the upper side of the penultimate pinna sometimes much larger tlian those 

 on the lower side, especially the basal ii])per one ; ultimate pinna- of the 

 lower part of the frond and compound pinna; furnished with remote, ellip- 

 tical, oblong, or subrhombic pinnules, which pass in ascending into lobes 

 and teeth of the same nature. In the pinnules of the lowest portions the 

 nerves are composed of a midnerve which sends off flabellately diverging 

 branches, which are forked or simple ; in the lobes and teeth of the ujjper 

 portions they consist of a midnerve which branches- several times, begin- 

 ning near the base, the branches diverging flabellately, or of a lateral nerve 

 in each lobe which forks once or twice. 



Locality: Fredericksburg; not rare. 



A number of good specimens of this plant were obtained. I have, 

 with a good deal of hesitation, united under this species a nundjer of forms 

 which differ somewhat in aspect, but there seems to be such a transition 



