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library 
NEW YORK 
Botanical 
Garden. 
On the Structure of the Palaeozoic Seed 
Mitrospermum compressum (Will.). 
BY 
AGNES ARBER, D.Sc., F.L.S. 
With Plates XXXVII-XXXIX, and two Figures in the Text. 
Contents. 
PAGE 
I. Introduction . .491 
II. General Characters of the Seed : 
A. The Sclerotesta.492 
B. The Sarcotesta ......... 495 
C. The Inner Flesh ........ 496 
D. The Vascular Supply ....... 497 
E. The Nucellus and Embryo-Sac.497 
III. Histological Details : 
A. The Sclerotesta. . 499 
B. The Sarcotesta ..499 
C. The Seed-Base ......... 500 
D. The Vascular Tissue . .c;oi 
IV. Nomenclature : 
A. Specific Name ..501 
B. Generic Name ......... 502 
V. The Attribution to CorJaites .504 
References .506 
Explanation of Plates.507 
I. Introduction. 
T HE numerous fossil seeds occurring in the Palaeozoic rocks have been 
conveniently grouped by Oliver 1 under the names Platyspermeae and 
Radiospermeae, these names corresponding to the two series originally dis¬ 
tinguished by Brongniart . 2 As the words imply, the Platyspermeae are 
flattened seeds with a bilateral symmetry, while the Radiospermeae are 
radially symmetrical. Our knowledge of the internal structure of the 
Radiosperms has of late years progressed very rapidly. To realize this 
we need only recall the memoirs on Lagenostoma Lomaxi , 3 Stephano - 
spermump Trigonoccirpnsp and Physostomap which all fall within half 
1 Oliver (’ 03 ). 2 Brongniart (’ 74 ). 3 Oliver and Scott (’ 04 ). 
4 Oliver (’ 04 ). 5 Scott and Maslen (’ 07 ). 6 Oliver (’ 09 ). 
[Annals of Botany, Vol. XXIV. No. XCV. July, 1910.] 
I. 1 
