146 NATHORSTIA. 
probable that Schenk’s specimen may be identical with the Sussex 
examples referred to Wathorstia. It not infrequently happens that 
the same specific and generic names have been used for Palseozoic 
and Mesozoic ferns, which have no resemblance to one another ; 
and this confusion no doubt arises from the choice of terms for 
new species from one geological horizon, without sufficiently 
considering the names already in use for plants of a different 
age. An instance of this is afforded by Pecopteris Geinitzi2, 
Dunk.; this name was instituted by Dunker' in 1846 for some 
specimens of Wealden fern fronds from Northern Germany; in 
1849 Gutbier? makes use of the same name, apparently without 
knowledge of its previous existence, for some Permian specimens 
from Saxony. Gutbier’s species is retained in Sterzel’s recent 
Monograph on ‘Die Flora des Rothliegenden im plauenschen 
Grunde bei Dresden,” * but, in view of the priority of Dunker’s 
application of the specific name, some new term should be sub- 
stituted in the case of Gutbier’s Permian plant. Schimper* 
includes Gutbier’s species under Pecopteris (Cyath.) pinnatifida 
(Gutb.), Gem. Some of the pinnules in the pinne figured by 
Schenk appear to show venation, but there is not sufficient 
evidence in favour of the identity of his specimen with those 
from the English Wealden to warrant our acceptance of the 
venation characters as characteristic of Wathorstia valdensis. If 
specimens are found which are clearly of the same species as those 
represented in Pl. VII. Fig. 5 and Pl. IX. Fig. 2, and show distinct 
venation of a type characteristic of some existing provisional genus, 
then the name athorstia must be abandoned. 
There is a certain resemblance between the present species and 
Alethopteris cycadina, Schenk, as figured in pl. xxvi. fig. 6, 
Paleontographica, vol. xxiii; but the agreement is very slight, 
and the earlier figure of the same species by Schenk® represents an 
entirely different plant to Nathorstia valdensis. 
1 Wealdenbildung, p. 6. 
2 Die Verstein. Roth. Sachsen. 1849, p. 16, pl. ii. fig. 10; pl. ix. figs. 1-3; 
pl. xi. figs. 5-6. 
3 Abh. math.-phys. Cl. k. Sachs. Ges. Wiss. vol. xix. 18938. 
4 Trait. pal. vég. vol. i. p. 507. 
5 Paleontographica, vol. xix. pl. xxxi. fig. 2. 
