245 
Cycadales. 
$ 12. Cycas revoluta, Thunb. 
Literature: Stopes (145, 146). 
Material: Bot. Gard. Lisbon. 
Figure: 145 p. 438. 
In the genus Cycas the sporophyll is a distinct foliar 
organ, more or less divided into lobes, bearing the ovules 
on its margins. In contrast with the other genera of the 
Cycads, where are always only two ovules on each 
sporophyll, here their number may be greater. 
The ovule (which name I will use in this and following 
descriptions, for the whole female organ borne on a 
megasporophyll) is bilateral symmetrical, with a length of 
about 3 cM. and a greatest diameter of 2,7 cM. Ripe 
ovules are orange coloured and covered near the micro- 
pyle with hairs, whereas young ovules are wholly clothed 
by a dense hair covering. 
The testa is very thick and composed of the three 
layers already mentioned in the former descriptions of the 
pteridospermous seeds. 
The sarcotesta is formed by large, thinwalled undifte- 
rentiated cells, filled up with starch, and there are many 
mucilage canals and tannine cells within it. Outside is an 
epidermis composed of radial-elongated cells with thick 
outer and radial walls, which is very characteristic for the 
whole genus. 
The sclerotesta is thickest at the top and near the cha- 
laza. In the chalazal region it slightly protrudes, accom- 
paning the vascular bundle entering the seed. The cells 
are thickwalled and two layers are to be distinguished, an 
inner one with cells elongated in a longitudinal direction and 
an outer one with cells directed in a more horizontal plane. 
The endotesta is well developed, nearly 4 mM. thick, 
