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Davie. — The Structure and 
sion of part of its xylem, or by its breaking up into a series of isolated 
strands, just as the leaf-trace of Dicksonia Barometz breaks up into a series 
of strands arranged in horseshoe fashion in the petiole (Gwynne- Vaughan, 
’ 03 , Fig. 17). In some cases (e. g. Onoctea and Las tre a) the abaxial face 
has been suppressed, but later on resumes its position. In other cases short 
portions of the sides have been dropped out, causing a trace of several 
strands to result. These would seem at first, as in the type of Lomaria 
Spicant , to have been inserted right at the base of the gap. Later they 
became extended up its sides but kept to its lower half, as in the Peranema 
and Diacalpe type ; while ultimately they became distributed well over the 
sides of the gap, extending into the upper half as well as occupying the 
lower, as in Nephr odium filix-mas. It is curious that no case has been 
found in which the several leaf-trace bundles, such as occur in Nephr odium 
filix-mas , fuse together in the petiole to form the single strand, while in cases 
with the Onoclean leaf-trace the single strand is regularly found in the 
petiole below the first pair of pinnae. But it would seem probable, at 
least, that development has gone along a line of breaking-up of the single 
horseshoe-shaped strand into several parts (Tansley, ’ 08 , p. 120), of the 
retention of these at first towards the base of the leaf-gap, and later of their 
extension up the arms of the gap. It would appear on this view that 
Peranema and Diacalpe come structurally very close to N ephr odium filix- 
mas , but that they show scarcely so advanced a condition of the arrangement 
of the leaf-trace bundles on the dictyostele as does that Fern. 
The discussion of the relationship of the pinna-traces to one another in 
different groups of Ferns must be left for a future paper. 1 It will suffice to 
say at present that, while Peranema , Diacalpe , and N ephr odium filix-mas 
show exactly the same type of pinna-supply, the criterion of marginal 
or extramarginal departure of the supply cannot be held as valuable among 
the different groups. That there is some constancy in the type of pinna- 
supply in Ferns of the same group has been shown by P. Bertrand (’ 09 ) 
and Gordon (’ll) for Clepsydropsis , Diplolabis Romeri , and Metaclepsy- 
dropsis duplex. The vascular details in the leaves in Peranema , Dia- 
calpe , and Nephrodium filix-mas are, however, identical. Such a fact may 
have some weight in confirming an affinity of Peranema and Diacalpe 
with N ephr odium. 
The presence of glands and of stalked hairs bearing glands would seem 
to indicate a relationship for Peranema with Lastrea . Glands are present 
internally in the rhizome and at the base of the petiole in Nephrodium 
filix-n>as (Sachs, p. 439 ; de Bary, pp. 89 and 220), internally at the base of 
the petiole in Aspidium spimilosum (de Bary, p. 220), externally on petiole 
1 The question has already been discussed for the Osmundaceae by Sinnott (TO) and Gwynne- 
Vaughan (’ll). 
