LOWER DEVONIAN PLANT REMAINS 119 
Stalk is about 0-75 mm. wide, and approximately 6 mm. long. The 
capsule measures 3-6 mm. in length and 2 mm. in breadth, and is 
slightly tapered towards the rounded apex. The margin is not 
preserved in the solid as in the previous example, but a curved 
ridge which follows the outline of the capsule a short distance 
within the margin appears to mark off a central dome-shaped area 
from a peripheral zone. The central portion occupies an area 
within the capsule of 3 mm. by 1-75 mm. It is lighter in colour 
than the rest of the specimen because of the partial removal from 
it of the reddish mineral substance that has replaced the plant 
tissues. The significance of these two areas is not clear. 
The remaining specimens, apart from providing a range in size, 
do not help in the more exact determination of the fossils. The 
nur of the smallest specimen is 2-5 mm. long and 1-5 mm. 
road. 
These specimens must be considered in relation to two simple 
Lower Devonian plants. They are Sporogonites and Cooksoma. 
In both, slender leafless axes terminate in large sporangia. In 
Sporogonites the axes, as far as is known, were unbranched. This 
feature has been remarked upon by Halle (1936) and Lang 
(1937). In Cooksonia, on the other hand, dichotomous branching 
of the axes which bear the sporangia is of usual occurrence and 
frequently takes place only a short distance behind the sporangia. 
For this reason and in spite of a rather close similarity as regards 
size and shape of their sporangia to those of Cooksoma sp. from 
Llanover, Wales (Croft and Lang 1942), it seems inadvisable to 
identify the present specimens with this genus. 
Comparison with Sporogomtes appears closer. Two species are 
known, S. exuberans from Norway, Belgium and Wales, and S. 
chapmani from Victoria. The capsules of the Lilydale specimens 
are distinctly smaller than typical examples of either species. A 
considerable variation in size, however, has been noticed in S. 
exuberans forma belgica by both Lang (1937) and Stockmans 
(1940), and a small form of S. chapmam has been described as 
forma minor. The grooving of the basal region of the sporo- 
gonium, evident in both S. exuberans and S. chapmani, is also not 
a constant feature and its absence from the Hull Road fossils 
acquires less significance when the unsatisfactory nature of the 
preservation in this soft shaley deposit is taken into account. To 
the nature of fossilization may perhaps also be attributed the 
apparent absence from the Lilydale specimens of the clearly 
defined sterile basal zone which is such an interesting morpho- 
logical feature of the capsules of Sporogonites. In view of these 
considerations a modification of the earlier record of these speci- 
