THE LEAF-TRACE IN SOME PINNATE LEAVES. 
form this pinna-trace. The segments of the leaf are much larger in L. cuspidatus 
and L. tricuspis than in L. guianensis, but in L. guianensis the combination-type of 
pinna-trace is just as marked as in the other two. The resemblance of the method 
of pinna-supply in L. cuspidatus to that in most of the Cyatheacese has already been 
noted (Davie, ’14, pp. 352, 353). In the Cyatheacese the pinna-trace comes partly 
“ from the point where the adaxial arc or the xylem hook joins on to the abaxial 
a b e 
Text-fig. 7. 
curve,” and partly | from the abaxial curve itself at the point where it is folded 
inwards” (Gwynne-Vaughan, ’03, p. 724). This is exemplified by the pinna-trace of 
Cibotium barometz (L.) J. Sm. (text-fig. 7a, b, c ). The adaxial portion of the leaf- 
trace in this Fern gives off its contribution to the pinna-trace in extramarginal 
fashion (text-fig. 7a), just as does the adaxial portion of the leaf-trace of Leptochilus 
cuspidatus (Davie, ’14, text-fig. 2, p. 353), and, in much less marked degree, that of 
L. guianensis (above, p. 10, and text-fig. 4c). There is little doubt that in the 
Cyatheacese the long leaf and large pinnse have involved the development of a leaf- 
trace of complex outline (see Tansley, ’08, pp. 117, 126), and perhaps also the 
provision of the combination-type of pinna-trace. That the combination-type of 
b c 
Text-fig. 8. 
pinna-trace does not invariably occur in the genera of the Cyatheacese is shown 
by the example of Balantium culcita (L’Herit.) Klf. (Davie, ’14, text-fig. 1, p. 351), 
in which a modification of the marginal type of pinna-trace is found. But in genera 
probably nearly related to some of the Cyatheacese, e.g. Hypolepis tenuifolia (Forst.) 
Bernh., the combination-type of pinna-trace appears (Davie, ’14, p. 358). It occurs, 
too, in Ferns related to the Pteridese, e.g. in Histiopteris incisa (Thbg.) J. Sm., and 
Pteris ( Litobrochia ) macilenta, A. Rich., though not in many species of Pteris itself 
(Davie, ’14, p. 358). The leaf-trace of Lonchitis pubescens, Willd., a species 
apparently related to the Pteridese and probably also to the Cyatheacese, is repre- 
sented in text-fig. 8. There the pinna-trace is derived partly from the outwardly - 
turned maroin of the antero-posterior flank of the leaf-trace, and partly from the 
margin of a strip which extends across the abaxial face of the petiole from side 
to side (text-fig. 8c, d). This recalls the processes found in Hypolepis tenuifolia, 
Pteris macilenta, Histiopteris incisa, and Leptochilus tricuspis. On grounds 
