THE PTNNA-TRACE IN THE FEUNS. 357 



also marginal. In the genus Odontosoria both types appear. Odontosoria chinensis, 

 var. Veitchii (see above, p. 351), is pronouncedly extramarginal, but 0. retusa (Cav.) 

 J. Sm. is marginal. The marginal type occurs in Davallia assamiea (Bedd.) Bak., 

 D. bullata, Wall., D. dissecta, J. Sm., D. immersa, Wall., D. pallida, Mett., D. 

 pentaphylla, Bl., D. solida (Forst.) Sw., and D. solida, var. Jijiensis. 



This appearance of both types in a number of species within a family is repeated 

 again in the Asplenieee ; but in them the extramarginal type is restricted to certain 

 genera, the marginal type to others. 



A marked and consistent adherence to the extramarginal type is found in the 

 genera Blechnum, Doodia, Woodivardia, and Brainea. In Blechnwn attenuatum 

 (Sw.) Mett., B. brasiliense, Desv., B. capense (L.) Schlecht., B. discolor (Forst.) Keys., 

 B. Moorei, C. Chr., B. tabulare (Thbg.) Kuhn, Doodia aspera, R. Br., var. multifida, 

 and Brainea insignis (Hk.) J. Sm., the type of supply is like that seen in Didy- 

 mochlsena truncatula, the pinna-trace departing from the back of a very distinctly 

 incurved adaxial leaf-trace bundle. 



An even more pronounced form of the extramarginal type is found in Wood- 

 ivardia radicans (L.) Sm., where the large pinna-trace arches up almost before it is 

 free from the parent bundle, and then breaks into several separate strands. 



In Blechnum Banksii (Hk. fil.) Mett., B. lanceolatum (R. Br.) Sturm, and 

 B. Pater soni (R. Br.) Mett., the adaxial leaf-trace bundles are short and narrow, 

 and the number of tracheides in the hooked ends is quite small. The pinna-trace 

 is undoubtedly extramarginal, though only a few tracheides of the margin are 

 left when it has gone oft'. Blechnum occidentale (L.) is also extramarginal, but 

 approaches very closely to B. orientale, which is only just extramarginal. 



The other extramarginal members of the Aspleniese are Athyrium filix femina (L.) 

 Roth., Diplazium celtidifolium, Kze., and D. marginatum (L.) Diels, in which the 

 large pinna-traces go off from the back of wide leaf-traces with distinct terminal 

 hooks. The amount left of the original margin after the leaf-trace has gone off is 

 greater in Athyrium filix femina and Diplazium marginatum than in Diplazium 

 celtidifolium. 



In the genus Asplenium the supply is consistently marginal. In Asplenium 

 bidbiferum, Forst., var. Fabianum, and in A. bulbiferum, var. Hillii, A. adiantum 

 nigrum {h.), A. prsemor sum, Sw., A. obtusatum, A. tenerum, Forst., and A. ruta- 

 muraria (L.), species which differ from one another in size of leaf, in complexity of 

 leaf-segmentation, and in leaf-texture, the supply departs on the marginal plan. 

 Ceterach officinarum, DC, also supplies its pinnae from the margin of its leaf-trace. 



This division of a family between the one type and the other occurs also in the 

 Pteridese, where some genera show the marginal, some the extramarginal type. Two 

 genera show some species following the marginal type and others following the extra- 

 marginal. Trismeria trifoliata (L.) Diels and Adiantum sanctse catherinse, hort., J. 



Sm., and A. polyphyllum, Willd., give off their pinna-traces in the normal extramarginal 

 TRANS. ROY. SOC. EDIN., VOL. L. PART II. (NO. 11). 49 



