119 MR. E. 4. NEWELL ARBER ON TRIASSIC SPECIES 
1894. Cordaites (non Unger), Compter, Zeitschr. Naturwiss. Leipzig, vol. Ixvii. p. 225. 
1895. Zamia, Ward, 15th Ann. Rep. U.S. Geol. Surv. p. 350. 
? 1903. Neggerathiopsis (non Feistmantel), Zeiller, Flor. foss. Gites Charb. Tonkin, p. 149. 
It will be necessary to briefly consider the significance attached to this generie name, 
since the attribution of the fossils described here forms the main point of this 
communication. 
In the past there has been some difference of opinion as to whether certain fronds 
should be included or excluded from the genus Zamites, and the sense in which this term 
has been used by several authors has often been extremely vague. Brongniart * 
originally referred to the recent genus Zamia a fossil frond from the Kimmeridgian of 
France, now known as Zamites Feneonis, Brongn., which together with the British 
Jurassic frond Z. gigas, Lindl. & Hutt.t, may perhaps be regarded as among the more 
typical members of the genus. The term Zamites, also first instituted by Brongniart, was, 
however, applied by him to a subdivision of the living genus Zamia, and the same author 
included several fossils under it. It is now generally agreed that such a use of the 
name of a still existent genus cannot be justified, and consequently the term Zamites has 
been raised to generic rank. It has also been found that Brongniart's original definition 
required emendation, and several attempts have been made by different authors to 
construct a satisfactory generic diagnosis by a modification of his scheme, so as 
to give it a more exact significance and to make it capable of wider application. An 
excellent sketch of these proposals has been given by Prof. Seward 1, and so the matte: 
need not be referred to here at length. 
The first really satisfactory diagnosis was that given by Schimper in 1870 in his 
* Traité? which may be quoted here in extenso, in view of the inclusion within this 
genus of the species described in this paper :—‘ Folia quoad formam et magnitudinem 
valde varia, nunc ex ovato-oblongo acuminata, nune ex oblongo, nune e lineali-oblongo 
acuminata, regulariter pinnata. Pinnz plus minusve patentes nec rachi perpendicu- 
lariter insertze, lanceolatze, lineali-lanceolat:ze, oblong:e, acuminate vel obtuse, basi subito 
contracta plus minus distincte callosa rachis lateri anteriori adfixee, solide coriaces, 
nervis sat distinctis strictis, inter se parallelis, ad folioli apicem cum hujus margine 
abruptis ” $. 
This diagnosis specifies several points to which I also attach importance, namely, the 
great variation in the size and form of the leaf exhibited by different species, the sudden 
nature of the contraction in the breadth of the pinna near its point of attachment, the 
presence of a more or less distinct basal callosity, and the strictly parallel and straight 
course of the nerves. Schimper further emphasises some of these peculiarities in the 
paragraph following the above extract in his book. 
. A more recent definition of Prof. Seward | is as follows :—*'* Frond pinnate, pinns 
more or less obliquely inclined to the rachis and attached to the upper surface, apices 
* Brongniart (1828), p. 94. 
T Now referred to the genus Williamsonia of the group Bennettitex. 
+ Seward (1895), pp. 75-78. 
$ Schimper (1869), vol. ii. p. 151. || Seward (1895), p. 78. 
