an archaic type of Seed from the Palaeozoic Rocks . ioi 
the hairs, is I -6 millim., as compared with 2 millims. or more in normal 
specimens. The most striking feature is the tapetum (Fig. 29, tpi) which 
was unusually conspicuous and well-developed, and has been referred to on 
p. 99. The other feature of interest relates to the position occupied by the 
vascular strands, which is relatively far out in the ribs (Fig. 29, v.b.) as com- 
pared with the usual position in full-grown specimens (cf. Fig. 2, v.b). The 
most obvious explanation of this apparent anomaly is to be found in the 
probable immaturity of the deeper layers of the integument. Now if we 
suppose the layers with radial seriation, that are present in full-grown speci- 
mens, especially below the furrows (PL V, Figs. 5 and 6, PL VII, Fig. 28, r.f ) , 
to be the last portion to differentiate, this, combined with a general expansion 
of the seed, would bring about the necessary readjustment for the shallowing 
of the grooves ; in this way the ribs would become less prominent and the 
bundles would come to lie relatively deeper as the seed approached maturity. 
Were the preservation adequate in the specimen under discussion, traces 
of this inner meristem ought to be visible. 
12. Diagnosis. 
Physostoma (Williamson). 
Straight, ribbed seeds, radially organized, the ribs separating at the 
summit into a whorl of free arms which surround the pollen-chamber. 
The ribbed integument is coalescent with the nucellus as far as the 
level at which the arms separate. 
The summit of the embryo-sac tapers into a papilla which projects into 
the pollen-chamber as a hollow core, like the bottom of a wine-bottle. 
A vascular system enters at the chalaza, dividing at once into separate 
strands which run along the ribs and out into the arms. 
The nucellus contains numerous secretory sacs ; a tapetal zone is also 
present. 
1. Physostoma elegans (Will.). 
‘ On some fossil seeds from the Lower Carboniferous beds of Lancashire ’, 
Brit. Association Reports (Bristol), 1875, P- x 59- 
Lagenostoma physoides , Will., ‘ Organization of the Fossil Plants of the 
Coal-Measures,’ pt. viii, Phil. Trans., 1 877, p. 241, Figs. 77, 78, and 79. 
Sporocarpon ornatum , Will., loc. cit., pt. x, Phil. Trans., 1880, p. 510 and 
PL XVIII, Fig. 39 ; pt. xii, Phil. Trans., 1883, p. 469, and PL XXXI, 
Fig. 27. Sporocarpon anomalum , Will., loc. cit., pt. xii, Phil. Trans, 1883, 
P 474- 
Localities : Moorhouse ; Dulesgate ; Bacup ; Shore-Littleborough 
(abundant) ; Ashton-under- Lyne ; Halifax ; always in the seam-nodules. 
Horizon t Lower Coal-Measures. 
