6 Watson, TJie Cone of BotJirodendron mundnni. 



be present. This harder tissue tends to become more 

 abundant towards tlie lamina of the sporophyll. 



Passing through the sporophyll is a single vascular 

 bundle; this is very small but seems to be collateral and 

 orientated in the normal way. Its course is very simple, 

 emerging from the cortex of the stem it runs directly 

 through the leaf base, looping downwards at the exterior 

 of the horizontal portion, and then passing upwards into 

 the lamina of the sporophyll (See Fig. ^oi Plate). It is 

 surrounded, particularly on the upper side beneath the 

 ligule, with a great deal of tran fusion tissue of the type 

 common in the Lepidodendraceae ; this tissue in the 

 neighbourhood of the ligule nearly cuts out the ordinary 

 parenchyma of the leaf base. 



The sporangium is attached by quite a narrow neck 

 of tissue to the upper surface of the horizontal limb at 

 about the middle of its length, this neck is roughly 

 circular in transverse section, and is about as high as 

 wide, it forms a pedicel on which the sporangium is 

 seated (See Figs. 3 and 4 o{ Plate). The pedicel contains 

 no vascular tissue. Both micro- and megasporangia are 

 attached in the same way. 



The pedicel expands into the sporangium with the 

 wall of which its epidermis is continuous. The central 

 tissue of the pedicel forms a little cushion inside the 

 sporangium, and spreads out to form a lining layer to its 

 lower part. 



The sporangia are higher than they are wide either 

 radially or tangentially. 



The sporangial wall usually consists of a single layer 

 of cells which are square in section, but irregular equi- 

 diametric polygons in surface view ; they do not shew 

 any trace of the buttresses which occur in Calamitean and 

 sphenophyllaceous fructifications. 



