Bd. III: 14) 
TJIE MESOZOIC Fl.OKA. 
55 
groups have gradually been separated from Zamites and made into distinct form- 
genera; but the limits both of these genera and of Zamites proper are by no means 
satisfactorily established. Of the genera in question, Zamites, Otozamites, and Ptilo- 
pJiyllum are represented in the Hope Bay flora, and it will be sufficient to remark 
shortly upon the limits here assigned to these genera. 
To Zamites, as delimited in this paper, are referred fronds of which the most 
important characters are the following: pinnæ attached to the upper surface of the 
rachis, linear or tapering upwards from near the rachis, inserted by a base which is 
more or less, often very little, contracted and always symmetric, with or without 
callosity. With this definition of Zaniites, Natiiokst’s Zamiophyllum is kept separ- 
ated from that genus. The forms included in Zauiites may be divided into two 
groups, which are however not very distinct. To the first are referred forms gener- 
ally considered as typical representatives of Zamites, i. e. with the pinna-base rounded 
and strongly contracted and swollen into a callosity. As the type of this group may 
be regarded Z. gigas (Lindl & Hutt.), and the group may be named Euzamites. 
In the second group, the pinnæ are not so broadly rounded at the base, but have 
the same breadth right down to the point of insertion, where they are very rapidly 
and very little contracted, without or with an indistinct callosity. The contraction 
at the base is often ver}" indistinct and can be seen only on careful examination. 
In such cases it is difficult to decide whether a specimen should be referred to Za- 
mites or not. As types for this second group may be regarded Z. borealis, Z. 
speciosus and Z. arcticus from the Kome Beds of Greenland (flEEK 1873), and the 
group may be named Subzamites. 
Otozamites and Ptilophyllum both differ from Zamites by having asymmetrical 
bases. To Otozamites are referred here forms with contracted, asymmetrical and 
auriculate pinna-base having the anterior lobe more developed than the posterior, 
which is more or less rounded. The asymmetry of the base caused by the stronger 
development of the anterior lobe is the essential character, since it constitutes the 
only difference from some members of the Subzamites-grovi'p. Ptilophyllum is employed 
here in Feistmantel’S sense. The pinna-base is asymmetrical, both edges bending 
downwards in joining the rachis; at the upper corner the base thus becomes rounded 
and for some distance free from the rachis, and sometimes a little auriculate; at the 
lower, it is decurrent on the upper surface of the rachis. When the bending down 
of the edges in joining the rachis is very slight, it is difficult to distinguish Ptilo- 
phyllum from some forms of the group Subzamites; but otherwise the genus, in 
Feistmantel’.S sense, is a very characteristic one. 
