671 



of relatively large elements, two anus, the antennae, are given off 

 at each side; they are slightly recurved and prominent at the outer 

 side at llieir insertion into the apolar. Thus a more or less well 

 developed sinus is formed. The endodermis but slightly incurves 

 on both sides of ihe vascular bundle. 



When followed in its downward couise, the pina-bar fuses with 

 the peliolai' bundle; the ends of the xyleni of the pinna-bar fuse 

 with the two prominences on both sides of the sinus (N°. 140). 

 Thus an elliptical mass of parenchymatous, or at any rate thin- 

 walled tissue, is enclosed. At a lower level, ns seen in section 141, 

 the pinna-bar has wholly fused with the petiolar bundle ; the enclosed 

 parenchyma has diminished in size, especially in breadth. The 

 [)eripheral looji, the downwards prolongation of the piniiabar has 

 diminished in thickness and is but a few elements thick in its 

 middle part. 



At a still lower level its continuity is interrupted; now on the 

 surface of the rather flat xylem a deep sinus is seen, which is 

 bordered on both sides by prominent ridges of tracheides. These 

 become nu)re rounded a( a lower level, and the original condition 

 is reached again. 



The continuity of the peripheral loop which is formed l)y the 

 fusion of the pinna-bar with the petiolai- bundle occurs in 2 of the 

 sections of the Groningen collection. It is nol shown in the Lonilon 

 specimens. But in these the well developed sinus is clearly shown; 

 in this feature they differ iniu'h from Ihe other species of the genus. 

 It is on these grounds that Scott distinguishes in his Catalogue this 

 form from the other species; it is shown here thai the deeper sinus 

 is not an independent character but caused by the fusion of the 

 piiuia-bar, when still coutinous, with the petiolar bundle; a feature 

 which is aberrant from that usual in the genus. 



If one tries to make a stereomelrical model of this structure, the 

 result is shown in tig. 4. In the other species of Etapteris e.g. 

 E. Scoiti Berti'and, the pinnae-bundles are also placed in pairs aiul 

 fuse on their downward course in tlie cortex. But at a slightly 

 lower level before their fusion with the petiolar bundle, the pinna- 

 bar is split up, and the two bundles resulting from this division 

 fuse independently with the vascular bundle of the petiole. An 

 amount of parenchyma is thus never enclosed by the fusion of the 

 petiolar bundle with the vascular tissue coming from Ihe pinnae. 

 That this difference with the features in E. Berlrandi is but a relative 

 one is shown by comjiaring the model of the structui-e of E. Scolli 

 (fig. 5) with that of the former species. Here we see the pinna-bar 



