[ 109 ] 
VII. On Triassic Species of the Genera Zamites and Pterophylldm: Types of Fronds 
belonging to the Cycadophyta. By E. A. NEwELL Arsth, M.A., IS. US 
Trinity College, Cambridge ; University Demonstrator in Paleobotany. 
(Plates 17-19.) 
Read 20th June, 1907. 
CONTENTS. 
l Page 
aa E uis os 65. pe E LL. Ja Bie i Ans, AAT QA; 109 
CONTAIN OM AON, v: bollaate. Seas A i uo chr Died 111 
SEA NEUE. LV cnr sor GV Les Reds DE E co 111 
mite Deos CUTE graltiqu, HOM, NOV. creer een 113 
(1) Synonymy, Localities, and Diagnosis ................... eee 113 
CGU Detenpuemrorthe Spermien cre is: Fe SLEVIN TL 114 
(5) Aue of the Bpis QE C. BLADE hl) eod. LAA bed... us 115 
Fe trophylium Brom Bobook suid. ocisex mali... elk « pon eum Dteyiet «os ui 119 
THU Gn Tropiu iioi sro ed raa P ab su eL Mi. na koe 119 
The Species Pterophyllum Bronni, Schenk stea.: serret uea aerer isere 120 
(1) Synonymy, Locality, and Diagnosis: iss < Si access ote vee ests 120 
(2) Description Of the Specie s utes rer Sie ee Cea etre ees 120 
(9) Affinities of the Species s srein AV IE a ASA IU INA IU 121 
GinblebCoaiusióng ^11 jails QUE eui 30d Lu ame 9. Feed 124 
PROUGGPOTAY a. cevodUo - esi - sdolenyr ^ es FARE EEE S. QUEUE D RE CÉ Lo 125 
Joe manttion of the Plates 1:5. oi, cs asd CE het Pca ULL. SIE Reed em 127 
INTRODUCTION. 
It is now a thoroughly established fact that the general aspect of the Mesozoic vegetation 
of the Rheetic, Jurassic, and Lower Cretaceous rocks differed entirely from that of the 
Paleeozoic floras. In recent years our knowledge of the various representatives of plant 
life which succeeded one another during these two great epochs has been so greatly 
advanced that we are now ina position to inquire into the nature of the change from 
the older, Paleeozoic, to the newer, Mesozoic, facies. Was it, on the whole, abrupt—a 
sudden transformation—or was it gradual and imperceptible? In the latter case we 
should expect to discover evidence of a well-marked transition flora, composed partly of 
old, partly of new types. | i 
In this connection it is interesting to find that we can trace back the first incomings 
of several of the more important Mesozoic races to sediments of Palæozoic age. It seems 
clear that some at least of these groups, especially the Cycadophyta, which in Mesozoic 
times attained to the position of ruling or dominant races, did not spring into exisfence 
Suddenly. The advent of the Cycadophyta is foreshadowed in both the Carboniferous 
SECOND SERIES.—BOTANY, VOL. VIL. s 
