110 MR. E. A. NEWELL ARBER ON TRIASSIC SPECIES 
and Lower Permian rocks, and, to a greater extent, in the sediments lying between the 
Permian and Rhetic deposits. During Paleozoic times, however, other and older types 
of vegetation were dominant, while the Cycadophyta were as yet in the infancy of their 
development and formed a subsidiary group; a fact which is emphasised by their 
infrequent occurrence and lack of diversity. 
Omitting from the list Gceppert’s * Cycadites taxodinus, from the Lower Carboniferous 
(Culm) of Silesia, as founded on too imperfect evidence to be regarded as a satisfactory 
representative of the group, we find in the Upper Carboniferous of the Northern Hemi- 
sphere leaf-impressions of several members of the Cycadophyta, all which, however, are 
very rare as compared with other genera belonging to typical Paleozoic races. The 
fronds known as Pterophyllum, a large genus and one of the earliest to attain to the 
dominant phase in Mesozoic times, more especially in the Keuper and Rheetic periods, 
is known from the Westphalian division of the Coal Measures of France+ and from 
the Upper Carboniferous and Permian of Germany 1. 
The genus Neggerathia, a name now applied in a restricted sense, is exclusively 
Westphalian in age. The attribution of this genus to the Cycadophyta is, however, 
doubtful §. Other genera, such as Zanittes || and Plagiozamites f, also appear on this 
horizon in the coalfield of Commentry, in France, and the latter also in beds of the same 
age in the Vosges. Zalessky ** has recently shown that Plagiozamites is associated in 
Manchuria with a Stephanian flora. The genus Sphenozamites +f} appears first in the 
Lower Permian near Autun, in France. 
In the Permo-Carboniferous flora of India and the Southern Hemisphere (Glossopteris 
flora), a Pterophyllum of the subgroup 4nomozamites is known, as well as a specimen 
doubtfully referred to the genus Cycadites 11 
Thus we see that a large number of the more important frond-genera of Cycadophyta 
are now known from the Paleozoic rocks, though others, such as Podozamites, 
Otozamites, and Dioonites, have so far not been found in formations older than the 
Mesozoic period. 
In the present communication two very interesting fronds are discussed, one belonging 
to the genus Zamites, recorded now from both the Bunter and Keuper divisions of the 
Trias, and for the first time from British rocks; the other, provisionally referred to the 
genus Pterophyllum, from the Keuper rocks of Carinthia. Both these leaves have been 
previously described on several occasions, and, as we have seen, these genera have been. 
already recognised from sediments of Palwozoie age. These particular species, however, 
have been the cause of much perplexity and confusion in the past. Both the fossils 
* Goeppert (1866), p. 131, pl. 2. figs. 1-3. 
t Zeiller & Renault (1888), p. 619, pl. 68. fig. 1; Renault & Zeiller (1886), p. 326. 
$ See Solms-Laubach (1891), p. 85. 
$ See Solms-Laubach (1891), pp. 141 and 151. 
| Renault & Zeiller (1886), p. 327; Zeiller & Renault (1888), p. 614, pl. 67. fig. 7 
"| Zeiller (1894), p. 174, pl. 8. figs. 1-5, pl. 9. fig. 1; Zeiller & Renault (1888), p. 615, pl. 67. fig. 8 
** Zalessky (1905), p. 401, text-figs. 13-15. 
tt Renault (1881'), (18817), (1893), p. 327, pl. 81. fig. 1. 
$t Arber (1905), pp. 208-210. 
