42 ROYAL SOCIETY OF CANADA 
ZAMITES TENUINERVIS, Fontaine. 
Hontaine, Potomac) Mora, "rl SPLIT NTI XV MR SR VIE 
TX TITI ÉTENERER TV 
Potomac Formation of Virginia; Trinity Division of Glenrose, Texas: Lower 
Cretaceous of Alliford Bay, Q.C.I. 
Two small fragments which cannot be distinguished from 
Fontaine’s Z. tenuinervis. 
NILSONIA POLYMORPHA CRETACEA (Sch.), New Comb. 
Schimper, Traité de Paléontologie, I., 489. Atlas, XLV., fig. 6. 
Lower Cretaceous of Maud Island, Q.C.I. 
The specimen consists of the terminal portion of a pinnate frond 
apparently of considerable length. Portions of 10 pinnæ are present, 
some of them perfect. They are alternate, of uniform width, with 
truncated or rarely acute ends which are turned up so as to give the 
pinna a falcate form, and they diverge from the rachis at an angle 
of 70 degrees. The only other Nilsonia recorded from the same 
horizon in adjacent localities, is N. lata Dn., from Baynes’ Sound, 
Vancouver Island! The difference is such, however, as not to admit of 
a comparison of the two. N. polymorpha of Schimper is represented by 
a frond about 25 cm. long and 3-5 cm. wide. The pinne in the middle 
diverge at an angle of 70-75 degrees, and they are distinctly falcately 
curved with acute ends. As the apex of the frond is approached, 
the divergence becomes reduced to 70 degrees, the falcate form 
becomes obscure or is altogether lost, and the acute apex is replaced 
by a truncated extremity. In these last features we recognize an 
almost exact duplication of the characters which distinguish the Maud 
Island specimen, and when we recognize the permissible latitude which 
is expressed in Schimper’s observation that the species is remarkable 
for its polymorphism, it will appear that our specimen cannot be 
satisfactorily separated from the type of N. polymorpha. Schimper 
records that this species is first found in the Rhetic Formation of 
Europe, and that its greatest development occurred during the period 
extending from the Rhetic to the Lower Lias. It therefore belongs 
in Europe, not only to the earlier Mesozoic, but to a transitional age. 
The occurrence of this plant in the Upper Cretaceous of America has 
not been recorded heretofore, and it would therefore seem appropriate 
that the present representative should be designated as N. polymorpha 
cretacea. 

1 Trans, R. Soc. Can, I., iv., 22 
