AS AIDS IN THE DETEEMINATION OF SPECIES. 23 



Central cauals vary amoug the four forms possessing them, from ^ in. {fici- 

 folia) to -i- in. (calophylla), taking the largest in each case for comparison. 



The vessels varied in width from^ in. (lehmanni) to -5^5 m. (gomphocephala) , 

 comparing only the largest in each species. 



Thus the largest section and thickest epidermis was found in tetraptera ; the 

 widest cortical cavity in globulus, although it is closely approached by cornuta ( i in.), 

 and the greatest width of vessel in gomphocephala, but globulus, tetraptera, and 

 citriodora almost equal it, with a width each of ^J,, in.' 



The characteristic nature of the wood-curve has already been insisted on, and it 

 may be added that the extent of development of the hard bast in the different species 

 seems to be a very constant feature. 



I. — FoKMs Confined to Westeen Australia. 



The following descriptions of the various sections are not merely based upon the 

 type-sections photographed, but are drawn in each case from a considerable number 

 of independent sections, of which camera lucida drawings were made. The usual 

 method followed was to make outlines of several sections from the same petiole as 

 that which supplied the type section, then from different petioles, and lastly from 

 herbarium specimens, at least three years old, to test the capability of the system for 

 determining museum material. 



1. E. occidentalis,^n^\iQhQV, fiat-topped Yate. 

 Shrub or tree, rising to 120ft. 



Leaves. — Of thick consistence, equally green on both sides. 

 Size of Section. — -1 line broad by | line thick, or about IJ times broader than 



thick. 

 Outline of Section. — Round to oval. 

 Epidermis. — Thickness, 5^0 ^'^■J l^i'eadth, —^ — ^ in. 

 Cortical Cavities. — nui"-' roundish, numbering from 8 to none, and therefore 



variable. 

 Crystals. — Numerous. 



Hard Bast. — Interrupted ring, sometimes only 1 cell thick. 

 Wood-curve (see Fig. 11). — Body thickened at centre, short horns, and sharply 



or gently inturned. 

 Vessels. — Largest, ~ in. in dia. 



A-verage, ^ in. 



Comparatively large and numerous, and distributed pretty regularly. 



