76 Salisbury . — On the Structure and Relationships of 
X. Relation to Vegetative Organs. 
In two of our series of sections there occur, associated with the seed 
structures, Medullosean petioles of which portions of as many as three are 
present in one and the same preparation. This fact would, in the light of 
present knowledge, 1 appear of itself significant, and, added to this, numerous 
secretory elements are present in these petioles which agree in structure 
with those found in the sarcotestal tissue of Trigonocarpus Shorensis. Each 
is enclosed by a sheath-like layer of somewhat flattened cells, and the wall 
surrounding the dark carbonaceous mass in the centre exhibits externally 
the characteristic longitudinal striations. Both of these features are also 
exhibited in the stems and petioles of Medullosa anglica. 
The individual bundles are collateral in structure, the phloem being 
represented by an empty space upon which the smallest protoxylem 
elements abut. The xylem is surrounded by a band of sclerotic fibres in 
close contact with the tracheides. The xylem exhibits no admixture of 
parenchymatous elements, so that in all respects the bundles are distinct 
from those of Rachiopteris W illiamsoni , 2 but agree very closely with those 
of Myeloxylon . 3 If, then, the petioles above described really belonged to the 
plant which bore our seed, the petrifaction known as Myeloxylon probably 
represents an aggregate of petiolar structures corresponding to at least two 
species of Trigonocarpean fruits, and possibly in both cases having as their 
stem a structure of the Medidlosa anglica type. In any case, the evidence at 
present available is against any suggestion that Trigonocarpus Shorensis 
was the fructification of Sutcliffia insignis i though the above association may 
be entirely without significance. 
The presence of numerous secretory ducts is a feature shared by both 
the known British Medullosean stems. In the structure of the chalazal 
bundle, whilst the protoxylems of Trigonocarpus Shorensis appear to be 
grouped in pairs (a feature of Sutcliffia insignis ), in the presence of internal 
parenchyma and a secretory duct within the xylem our sections of 
Trigonocarpus Pai'kinsoni show a closer agreement with that stem. 
XI. Diagnosis. 
Trigonocarpus Shorensis , sp. nov. 
Locality : Shore Littleborough. 
Horizon : Lower Coal Measures. 
A radially symmetrical obovoid seed tapering to its insertion and 
circular in transverse section. Length over 4 cm., width 2-4 cm. 
1 Scott, Progressus Rei Botanicae, vol. i, p. 206. 
2 Seward, Ann. Bot., vol. viii, No. 30, 1894, p. 208. 3 Ibid., vol. vii, 1893, p. 1. 
