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uppermost ones, which form the fructification properly, 
they are hardly to be observed. The sporophylls are 
placed nearly on the same level with one another, so that 
they give the impression of forming a whorl of four bracts. 
They are large and soon become lignified closing together 
and forming a berry-like structure as in àll Cupressaceae, 
the apices of which are replaced on the dorsal side. 
On its apical surface each sporophyll bears two to 
numerous erect ovules, which in mature condition are 
provided with two broad wings and become free by the 
separation of the sporophylls like four valves. 
In Callitris the integument has not been differentiated 
in the three layers, but remains thin and membranous, 
forming the above mentioned wings on either sides. Pro- 
bably to increase the capacity of the dispersion of the 
seed, large cavities filled with air, are found within the 
membrane. 
The nucellus is fused to halfway its height with the 
integument and is composed of a solid mass of cells, the 
beak of the pollenchamber pointing into the micropylar tube. 
In connection with the reducement of the differentiation 
of the testa, the vascular supply has been modified and 
remains as a tracheal plate at the base of the ovule. 
In the ripe seed a far developed embryo is enclosed 
within the soft nucellar tissue. 
$ 23. T'huya occidentalis L. 
Material: Bot. Gard. Lisbon. 
E Palermo. 
As in the female fructification of Callitris the mega- 
strobilus of T'huya is built up of four to five pairs of 
decussate bracts, which, however, are not sharply sepa- 
