26 T. G. HALLE, MESOZOIC DEPOSITS AND FLORAS OF PATAGONIA AND TIERRA DEL FUEGO. 
it is clear that the pinnae have a downward trend at the base and are attacched 
to the upper surface of the rachis. The specimen should therefore be referred to Ptilo- 
phyllum, and not to Pterophyllum, with which genus there is some habitual resem- 
blance. The difference from the species described above is rather great, the pinnae 
are much more distant, are longer and narrower and almost straight. Notwithstanding 
these differences, the specimen has here been referred to the same species, chiefly 
because there seem to have existed intermediate forms. One such specimen showing 
transition to the typical form is seen in pl. 3, fig. 12. It consists only of a small 
fragment, but it shows the arrangement of the pinnae, which is somewhat denser than 
in the specimen in pl. 3, fig. 11. 
It will be evident from the above description that the species should be referred 
to Ptilophyllum. "There is some uncertainty at present regarding the delimitation of 
this genus. As defined by MORRIS, it had a very wide extension, no regard being 
paid to the shape and attachment of the pinna-base. SEWARD (1903 a) appears to 
prefer to keep the genus in this wide sense of MORRIS, whereas FEISTMANTEL (1876) 
has tried to delimit it more narrowly in defining it, by means of the shape of the 
pinna-base, with reference to the allied genera Zamites and Otozamites. FEISTMANTEL 
attaches great importance to the downward trend of both edges at the insertion, 
and his opinion is borne out by the illustrations given by him of the Indian species. 
ZRILLER, in his definition of the genus in the Tonkin flora, accepts FEISTMANTEL'S 
delimitation. There can hardly be any doubt that the specimens figured by FEIST- 
MANTEL belong to the same species as MORRIS types of the genus. As the drawing 
of one of MORRIS” type-specimens published by Prof. SEWARD (1903 a, p. 228) shows 
a rather great difference in regard to the pinna-bases, however, matters are not quite 
clear. The best of MORrRis” specimens is the one shown in his pl. 21, fig. 1a: 
MORRIS” figure appears to agree well with those of FEISTMANTEL, but in order to get 
a better idea of this important specimen I have procured photographs of it from the 
British Museum. In the two photographs, one in natural size, one thrice magni- 
fied — for which I am greatly indebted to Dr. SMITH WOODWARD and Dr. M. C. 
StoPES — I am not able to see any difference from FEISTMANTEL'S figures. So far as 
the somewhat unsatisfactory state of the preservation permits of forming any opinion, 
the edges of the pinnae appear to bend downwards in joining the rachis just as is 
required by FEISTMANTEL'S definition. Everything considered, it seems to be best to 
accept FRISTMANTEL'S delimitation of Ptilophyllum. It must be emphasized that, even 
with this narrower definition of the genus, SEWARD'”S statements as to the close rela- 
tion of the Indian Ptilophyllum species and the English fronds referred by him to 
Williamsonia pecten (PHILL.) CARR. still holds true. Of the numerous forms included 
in the latter species both those of the type of Cycadites pectinoides PHILL. and C. 
pecten PHILL. have the same kind of pinna-bases as the Indian species, at least in a 
great majority of the specimens. There is, therefore, as stated by SEWARD, no generic 
difference between the European and the Indian forms. 
Of the species of Ptilophyllum hitherto described, P. acutifolium MORR. affords 
the most suitable place for the Patagonian specimens, and there is no difference of 
