63 
Zygopteris Grayi of Williamson . 
form a triangle. Dr. Bertrand believes that the median protoxylem-bands 
are in connexion with the protoxylem which passes out in the peripheral 
loops of the leaf-traces, though the connexion is often obliterated. The 
true protoxylem elements are accompanied by narrow scalariform tracheides, 
exactly as in Ankyropteris Grayi. There is, however, a difference in the 
fact that short, globular tracheides are also present in the ‘ mixed pith ’ of 
Asterochlaena ; I have not found these in our plant. 
Roots are inserted laterally on the leaf-trace, just where it leaves the 
stele, but they also occur on other parts of the xylem-arms. The structure 
of the roots exactly agrees with that of the roots associated with Ankyro- 
pteris Grayi. 
The outgoing leaf-trace gives off numerous lateral strands, which pass 
out in advance of the trace itself. Dr. Bertrand (’ll, p. 53) points out the 
manifest agreement with the strands in Ankyropteris which supply the 
scales (aphlebiae). In both cases the organs thus supplied have the value 
of secondary petioles. 
Asterochlaena might be described as a multiple Ankyropteris , for it 
differs most essentially from such a plant as Ankyropteris Grayi in the fact 
that each arm of the stele supplies two or three vertical series of leaf-traces 
instead of one. 
Dr. Bertrand, it is true, does not recognize so close an agreement 
between the two genera as seems to me to exist. He states (p. 50) that the 
Asterochlaenas are the only known Ferns which possess a system of 
protoxylem-bands proper to the stem. It seems clear that Ankyropteris 
Grayi and its allies are precisely in the same position. He also gives an 
interpretation of the Ankyropteris vascular system which separates it from 
Asterochlaena. In A. Grayi he regards the wood as constituted of five 
curved plates, concave outwards, the five ‘ reparatrices ’, each of which repre- 
sents the left-hand ‘ demi-reparatrice ’ of one xylem-arm and the right-hand 
‘ demi-reparatrice’ of the next (’ll, p. 52, Fig. 8 ; see also the text-fig. in this 
paper, p. 51). These * reparatrices’ alternate with the ‘generatrices foliaires’ 
(vertical lines of leaf-traces). On this view each leaf-trace is supposed to be 
supplied by the two xylem-bands lying to the right and left. In Astero - 
chlaena , on the other hand, the simple ‘ reparatrices ’ are placed directly 
behind the ‘ generatrices ’ in the same radial plane (p. 53). Personally 
I can see no distinction in this respect, except that the xylem-arms are 
longer in Asterochlaena. 
This whole conception of the Ankyropteris stele seems to me defective, 
for it ignores the internal xylem, which here, just as in Asterochlaena , 
‘represents, as it were, the skeleton of the xylem-star ’ (P. Bertrand, ’ll, 
P- 3 6 )- 
The object of Dr. Bertrand’s somewhat artificial interpretation of An- 
kyropteris structure appears to be to bring it into line with the vascular 
