77 
Trigonocarpus Shorensis , sp. nov . 
Testa differentiated into two parts : 
(#) Sclerotesta (length 2-8 cm., width 1.5 cm.) produced at the apex 
into a short triangular beak and bearing six ribs, viz. three principal and 
commissured extending throughout, and three minor and non-sutured 
reaching to some 8 mm. from the base, (b) Sarcotesta about 4 mm. in 
thickness, lacunar in structure with numerous secretory sacs, and six peri- 
pherally situated vascular bundles alternating in position with the ribs. 
Limiting layers containing sclerotic strands. Nucellus free, containing 
vertically directed secretory sacs, and limited within by vascular tissue 
forming a continuous lining at the base but above passing into separate 
bundles. 
XII. Summary. 
In the foregoing pages a detailed description is given of the Palaeozoic 
seed Trigonocarpus Shorensis , of which the chief diagnostic features are 
summarized in the preceding section. 
The sclerotesta differed principally from that of the well-known species 
in its obovoid form and tapering insertion, the absence of ridges in relation 
to the vascular bundles, and in the relatively short beak. In the early 
disappearance of the secondary ribs it resembled closely the external cast 
of Trigonocarpus corrugatus. 
Both sarcotesta and sclerotesta showed considerable complexity, with 
nevertheless a well-marked transition, such as can only be reconciled with 
differentiation of the same organic unit. The sclerotesta was built up of 
fibrous elements longitudinally directed within and without, intertwined in 
a complex manner. The sarcotesta was unusually broad, lacunar in 
structure, and contained numerous secretory sacs comparable to those 
of Cycads. 
The limiting layers were formed of a ground-tissue of parenchyma 
containing a system of probably anastomosing and tangentially flattened 
strands of fibres, with secretory sacs like those of the interior. The whole 
structure in this region approached much more nearly to that of the peri- 
pheral layers of a Medullosean petiole than in Trigonocarpus Parkinsoni . 
The sarcotesta exhibited no flattening, but was circular in form 
throughout, whilst an inner flesh was probably only present as an incon- 
spicuous layer within the micropyle. 
The vascular system comprised two parts, viz. a sarcotestal and 
a nucellar. 
The most notable feature of the former is the extreme peripheral 
position occupied by the six mesarch vascular bundles. 
The single chalazal bundle had the protoxylem groups just within the 
periphery, and expanded at the base of the nucellus into a tracheal cup, 
which was probably formed of twelve laterally fused bands that gradually 
