TON CNET rS Ts 
P TTE j 
OF THE BRITISH COAL MEASURES. 65 
The structure is the same as that of the leaf-base attached to the stem, 
excepting only the further subdivision of the bundles. In tbe two lateral 
bundles the xylem is divided, but still in connection. In the middle bundles 
the division is complete, the ground-tissue already separating the daughter- 
bundles of each pair (fig. 3). The structure of each bundle appears to be the 
same as in the xylem-strands of the stem, ¿. e. mesarch with little centrifugal 
wood. There is no appreciable change in the arrangement of the bundles 
throaghout the series. The ground-tissue of the petiole, like that of the leaf- 
base, consists of large-celled parenchyma, in which plates of sclerotic cells, 
and also isolated elements of the same kind, are embedded. 
The hypoderma is much thicker on the convex than on the concave side. 
On the former it is composed chiefly of thick-walled elements, with narrow 
radial bands of parenchyma at intervals resembling the hypoderma of the 
leaf-base. The thin layer of hypoderma on the concave side of the petiole 
seems to consist entirely of sclerenchyma, with smaller cells and thicker walls 
than that on the opposite face. Towards one end of the specimen (that 
corresponding to the lower end of the stem-fragment) the hypoderma on 
the concave side dies out. This is probably merely a matter of preservation, 
but it is possible that in this part the petiole or leaf-base was originally 
attached to its stem. 
The characters of the new species (for as such it must be reckoned in the 
absence of evidence to connect it with any other form) may be summed up 
as follows :— 
Heterangium shorense, sp. nov. 
Stem large, reaching a diameter of 18 mm. in the one specimen known. 
Primary wood arranged in small definite packets, separated by a reticulum 
of parenchyma. 
Secondary wood sinall-celled (little developed in the specimen). 
Peripheral xylem-strands and leaf-trace bundles mesarch, with little 
centrifugal wood. 
Selerotic tissue highly developed, both in the pericycle and inner cortex. 
Leaf-trace consisting of two bundles where it leaves the stele, dividing into 
four on entering the cortex, and further dividing into eight in the leaf-base 
and petiole. The traces of at least four leaves present in each transverse 
section of the stem. Leaf-traces traversing the stem for a long distance 
before passing out. 
Locality. Shore, Littleborough, Lancashire: Lower Coal Measures. 
Found by Messrs. James and Joseph Lomax, August 1912. 
