V] 



APHLEBIAE 



99 



Aphlebiae 



Under the name of aphlebiae certain lateral appendages of the leaves 

 of fossil Ferns and Pteridosperms have been assembled, which though cor- 

 responding in position to pinnae or pinnules differ from them in outline, 

 and apparently also in texture. They are irregularly cut or lobed, and they 

 often appear as though they were without venation (Fig. 95). Comparison 

 indicates that they are of the nature of pinnae or pinnules, arrested and 

 specialised for the protection of other parts while young. Their position on 



Fig. 95. Left, aphlebiae at the base of a petiole of the living Hemitelia capensis. Right, aphlebiae 

 on a leaf of Sphenopteris crenata, Lindl. from the Carboniferous Period. (After Schimper, from 

 Velenovsky.) 



the surface of the stem oi Ankyropteris Grayi, as well as on the leaf-base, but 

 still with vascular connection with the stem, suggested to P. Bertrand their 

 description as "sorties hatives," their insertion being at a point lower than that 

 at which the normal pinnation begins. A parallel is to be found in some 

 living species of Gleichenia {G. gigantea, Wall., is quoted by Potonie), while 

 in Hemitelia capensis and in a minor degree in other species of the Cyatheoid 

 Ferns, somewhat similar modifications of basal pinnae are found, which have 

 been described as aphlebiae (Fig. 95, left). There appears to be no sufficient 



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