45 
Trigonocarpus Shorensis , sp. nov. 
than the external form, and from the base of the micropylar canal measured 
some 19 mm. with a diameter in its broadest part of slightly over 14 mm. 
Sections through the micropyle (PI. IV, Fig. 2) show that the sclerized 
sides of the triangular canal about half-way up, formed of four layers of 
longitudinally directed fibres, were from 0-13 to 0*14 mm. in thickness and 
distinctly concave, the internal diameter of the canal measured from the 
apex of an angle to the middle of one of the sides being just over 2 mm. 
In the highest of our sections (PI. IV, Fig. 5 ) } viz. Man. Coll. R. 1161, b, the 
limit between sclerotesta and sarcotesta is indefinite and the diameter of the 
micropyle is reduced to 1*4 mm. On that side of this oblique section 
which is at the higher level the sclerized layer is seen to be even less 
developed than on the lower, and the concavity of the flanks has resolved 
itself into a slight double convexity (thickness between the' angles o-io mm. 
and at the convexities 0-16 mm.) (PI. IV, Fig. 8, m,c). 
Although this section is broken there is evidence that the sclerotesta 
towards the apex segregated into three distinct portions separated at the 
angles by intervening soft tissue and each itself composed of two parts fused 
in the median plane. 
Except for the slight local thickening, both here and in the preceding 
section, there is a thinning down of the sclerotic beak which, if maintained 
at the same rate, must have resulted in its complete elimination at a level 
not far above that at which our section was cut. 
From these facts it would appear that the beak was comparatively short 
(probably not more than 8 mm. in length), although the extensive develop- 
ment of the sarcotesta at this level and the curve which successive sections 
show its surface to have followed indicate a much further persistence of that 
tissue. So that in this respect our seed resembled most closely the condition 
that obtains in present-day Cycads. 
Histology of the Sclerotesta. The sclerotesta was formed of from 14 to 
15 layers of thickened fibrous elements, of which the inner, and most of 
those forming the ribs, were longitudinally directed. In the best-preserved 
specimens the innermost layer is seen to have been composed of radially 
flattened fibres which form a smooth internal surface, and negative the 
suggestion of a more interior tissue. In transverse sections the fibres appear 
rounded or polygonal (28-42 fx) with dark contents separated by a thin 
membrane (? middle lamella), on either side of which is a translucent yellow 
zone about 3-5 \x in width perhaps representing the cell-wall. The fibres 
consisted of superposed cells which can be traced for over 1-5 mm. 
The sclerotic fibres, 5-9 deep, forming the outer layers behave as 
aggregates or bands, each of from one to two elements in the radial 
direction and of a very variable number in the tangential (Text-fig. 5). 
For a time each band follows the longitude of the seed, and then almost 
abruptly all the fibres bend, some to the right and others to the left, or all 
