78 Salisbury.— On the Structure and Relationships of 
increased in number to form numerous mesarch lenticular bundles lining the 
inner limit of the nucellus. 
The nucellus was attached at the base to a sclerotic papilla, but was 
otherwise free from the testa, and its outstanding features were — a well- 
developed and thick-walled epidermal layer ; the occurrence of three 
longitudinal flanges, corresponding with the commissures ; and the presence 
of numerous secretory sacs in the ground-tissue, arranged in radial files. 
Two sections of Trigonocarpus P arkinsoni are described which indicate 
that the chalazal bundle gave off three branches simultaneously, which 
almost immediately bifurcated to form the six sarcotestal strands. 
A comparison with Cycads and allied types leads to the conclusion 
that Trigonocarpus Shorensis is in several respects a relatively more primi- 
tive type than its congeners. In this connexion Trigonocarpus Oliveri is 
shown to have been an eight-angled seed, and is therefore probably to be 
excluded from the Trigonocarpeae. 
In the general discussion on the testa, the evidence for its homogenous 
origin is set forth, and the theory is advanced that it had its inception in 
the lateral fusion of a whorl of six originally free members. The testal 
structure of the various genera is discussed in the light of this theory. 
The resemblances and differences between the Trigonocarpeae and 
Lagenostomales are shown to be explicable on the hypothesis of intercalated 
growth, followed by subsequent congenital fusion between the nucellus and 
integument. 
Medullosean petioles associated in the coal-balls with Trigonocarpus 
Shorensis are briefly described, and resemble Myeloxylon . 
EXPLANATION OF PLATES. 
Illustrating Mr. Salisbury’s paper on Trigonocarpus Shorensis. 
R = Owens College, Manchester, Collection ; S = University College Collection ; D.H.S. = Dr. 
Scott’s Collection. 
PLATE IV. 
Figs, i-io, photomicrographs. 
Fig. i. Nearly transverse section through the middle of the seed, showing the three commissural 
ridges (r 1 , r 2 , r 3 ) and the extensive sarcotesta ( st .). The nucellus is seen in part on the right with 
a ridge near the commissure slightly displaced («/.). The black dots in the sarcotesta are the 
carbonaceous contents of the mucilage sacs. R. 1161, h. x about 4. 
Fig. 2. Slightly oblique section through the micropyle, showing sarcotesta with secretory sacs 
(m.s.). Within the triangular sclerotesta the inner flesh can be faintly seen. R. 1161, £. x 2*5. 
