37 
Most of the leaflets are detached but they are closely associated in the shales 
and one specimen from locality CS2, which is the basis for the statement 
that the leaflets are five in number, shows four leaflets attached to the 
peduncle and a fifth in a position of attachment but lacking continuity by 
reason of a chip of shale broken out of the specimen. 
In the usual diagnoses of the genus four is given as the normal number 
of leaflets, although as few as two may be present, and Sagenopteris elliplica, 
if one may generalize from a limited amount of material in the Potomac 
Group, normally had five leaflets. 
As fossil species go Sagenopteris mclearni is the most distinctive of 
any of the described forms, which are normally variable in size and outline, 
and furnish few conclusive diagnostic characters. The genus is abundant 
in the Rhaetic, Jurassic, and Lower Cretaceous, and is represented by 
somewhat doubtful material from the European Upper Cretaceous. 
Sagenopteris mantelli (Dunker) Schenk. 
Plate V, figure 7 
Cydopteris mantelli Dunker, Wealdenbild., p. 10. PI. 9, figs, 4, 5 (1846). 
Adiantites mantelli Brongniart, Tableau, p. 107 (1849). 
Aneimidium mantelli Schimper, Pal. Veg6t., tome 1, p. 486, 1869; Atlas, 
PL 31, fig. 13 (1874). 
Sagenopteris mantelli Schenk, Palaeont. Bd. 19, p. 222; Seward, Wealden 
FI., pt. 1, p. 130 (1894); Fontaine, in Ward, U.S. Geol. Surv., 
Mon, 48, p. 233, PL 65, figs, 30-35 (1906). 
In this species the pinnules are small and elliptical, coriaceous, and 
stout veined. The specimens found sparingly at the Lower Blairmore 
locality CH2 are not distinguishable from material from the English and 
German Wealden. Sagenopteris fronds are notoriously variable and it 
may well be that this Lower Blairmore occurrence does not represent the 
European species, but that it should be referred to the associated and far 
more abundant, as well as variable, Sagenopteris elliptica. In fact, I am 
inclined to think that this is the true state of affairs. 
Genus, onychiopsis Yokoyama 
Onychiopsis psilotoides (Stokes and Webb) Ward 1 
This species, which by those who have no regard for the canons of 
nomenclature, goes under the name of Onychiopsis mantelli, has been referred 
to a variety of genera, including Hymenopteris, Aspidium, Sphenopteris, 
Thyrsopteris, etc. Very many supposed species of Thyrsopteris from the 
Potomac Group in particular belong here. Yokoyama was the first to 
recognize its similarity to the existing polypodiaceous genus Onychium, 
The present species is characterized by large tripinnate fronds, with reduced 
ascending, alternate, lanceolate-acuminate pinnules, serrately sub-lobate 
proximad; with fructifications of ovate, awn -like, sessile, or short-stalked 
terminal series. This species, which we might naturally suspect of being 
a composite one, has been recorded from the Neocomian and Wealden 
throughout the European Lower Cretaceous; from South Africa and 
Spitzbergen. On this continent it has been recorded from the Potomac 
1 For a MI synonymy and discussion of this epeeim See Barry, E. W.: Lower Cretaceous, p. 274 (1911). 
