SPORE-PRODUCING MEMBERS 407 
Comparing this with Fig. 225, which is from the axis of Calamostachys 
Binneyana, there is a similarity in outline of the primary stele; but as 
this is not constant in the species it cannot bear weight in the comparison. 
The points of importance are, the similar canals, of like position to those 
of S. zwsigne, and like them showing the position of the protoxylem; the 
continuous medullary rays, and the similarity of the tracheides. These 
Chetrostrobus Pettycurensis. Diagram. The upper part in transverse, the lower in 
radial section ; the position of the organs corresponds in the two sections. 1. Transverse 
section. Six complete sporophylls, each with three segments, are shown ; S/.a=section 
passing through sterile segments; $/.6=ditto through fertile segments, or sporangio- 
phores ; s¢=lamina of sterile segment ; s¢}=downward outgrowths of sterile laminae cut 
transversely ; s¢)=their apices, transverse ;_/=peltate sporangiophores ; s.77= sporangia. 
Note that in S/.a each peltate lamina, /, is seen in two distinct lobes, with the sterile lamina 
between ; v.64, v.d2=vascular bundles of two whorls. 2. Radial section. The sporophylls 
are separated from one another for clearness’ sake, in nature they are in close contact. 
Ax=axis of cone; cy=its stele; Zr=base of sporophyll. Other lettering as in trans- 
verse section. The diagram is true to nature as regards proportions of parts, as well as 
their relative position. about 2. (From Scott's Studies in Fossil Botany.) 
features appear to indicate a real structural resemblance, and it is important 
to note that the nearest approach is between the oldest of the Sphenophylls 
and the strobilar structure of a Calamite; for according to the views here 
advanced, it is in the strobilus that the more primitive structure might be 
anticipated. 
A special interest in relation to the strobiloid theory attaches to 
Sphenophyllum majus, with its ill-defined cone. It is important to note 
that this state, so prominent in Lycopodium, is found in that species 
