Mitrospermu in compressum {Will). 507 
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EXPLANATION OF PLATES XXXVII-XXXIX. 
Illustrating Mrs. Arber’s paper on Mitrospermum compressum (Will.) . 
The following abbreviations are used :— 
W. = Williamson Collection, British Museum of Natural History; D. H. S. = Dr. Scott’s 
Collection ; U. C. L., S. and R. = University College Collection, London ; Wat., A. = Mr. D. M. S. 
Watson’s Collection; M., R. = University of Manchester Collection. 
PLATE XXXVII. 
Figs. 1-6, 9, 10, photographs by W. Tams; Figs. 7 and 8, photographs by E. A. N. Arber. 
Fig. 1. Transverse section, probably near apex of seed, showing sclerotesta (sc.), and wing (w.), 
the latter preserved on one side only. U. C. L., S. 48 (Shore), x 20 circa. 
Fig. 2. Longitudinal section in secondary plane (i. e. plane at right angles to plane of flattening, 
(see p. 493) passing through the micropyle (mi.). This section is remarkable for the great develop¬ 
ment of the sarcotesta (j'a.) and inner flesh (if.), sc. — sclerotesta. U. C.L., S. 70 (Shore), 
x 33 circa. 
Fig. 3. Longitudinal section of another seed cut in the same plane as that shown in Fig. 2. 
The micropyle (mi.) is more widely open, and the sarcotesta (sa.) less developed, sc. = sclerotesta. 
U. C. L., S. 37 (Shore), x 46 circa. 
Fig. 4. Transverse section of a decorticated sclerotesta (sc.), showing a stigmarian rootlet 
(stig.) wedging the valves apart. U. C. L., S. 45 (Dulesgate). x 15 circa. 
Fig. 5. Base of oblique longitudinal section passing through the hilum (h.). sa. = sarcotesta ; 
sc. — sclerotesta ; n. and m. — nucellus and megaspore ; m.c. mucilage cells of sarcotesta. U. C. L., 
S. 60 a (Shore), x 21 circa. 
M m 
