iqi S ] AASE—MEGASPOROPUYLLS OF CONIFERS 299 



vegetative leaf. This is a characteristic which so far as investi- 

 gated occurs outside the Araucarineae only in Podocarpus Nageia. 

 The sporophyll of Araucaria is characterized by the so-called 

 ligule, which there is good reason to believe is homologous with 

 the scale described in the foregoing groups. In the young strobilus 

 of Araucaria Rulei and Araucaria Balansi the comparatively small 

 ligule is attached to the bract at its base only, the greater portion 

 being free. In the older strobilus it is free only at the tip. Distal 

 to the line of coalescence of bract and scale the bract remains thick 

 and wide, then becomes narrow and stiff, resembling the bracts 

 at the base of the strobilus. 



The vascular supply to the sporophyll of A. Balausi (figs. 

 142-154) arises as a single bundle near the base of the gap in the 

 strobilus cylinder. In the middle of the cortex the single bundle 

 divides into two unequal parts, the smaller of which twists through 

 an angle of 180 so as to lie above the parent bundle with its xylem 

 facing the xylem of the latter. The upper bundle may or may not 

 divide at this stage; the lower bundle divides into two or three; in 

 case of two, one bundle soon divides and a median lower bundle 

 is formed. The lateral bundles divide actively; some of the result- 

 ing bundles become inverted and lie on a level with the upper 

 bundle, others normally oriented come to lie on a level with the 

 lower median bundle. Where the sporophyll broadens, branches 

 with normal orientation enter the wings. Behind the ovules the 

 bundles of the upper series begin to converge in groups, and finally 

 end in masses of irregular tracheids. A bundle is sometimes found 

 to continue almost to the free portion of the ligule. Where the 

 bract becomes narrow, the lower bundles also end, with the excep- 

 tion of about three median ones which extend into the slender 

 portion. In the lowest sporophylls, where the ovule and scale are 

 poorly developed or absent, the upper bundles are weak and few 

 in number, or wanting. 



In the other forms investigated, A. Rulei (figs. 155-161) and 

 A . cxcelsa, the general features are as in the above-described species. 



The strobilus of Agathis australis (figs. 162-170) is composed of 

 numerous sporophylls which are very closely packed, probably 

 owing to the shortening of the strobilus axis. A ligule, as found in 



