JEFFREY. — ARAUCARIOXYLOX TYPE. 565 



time, a few years at most. The writer has discus-sed and figured 

 woods of this type in a ineinoir on the Coniferous remains found at 

 Kreiseherville, Staten Island. ^^ It is aecordingly uimeeessary to do 

 more than eall attention to their characteristic features here. It has 

 been pointed out in the second article of this series that peculiarities 

 of pitting and other features, found in Mesozoic woods of this type, 

 to which the writer has given the generic name Brachyoxylon, are 

 likewise found in the seedling axis and the cone axis of the living genera, 

 Agathis and Araucaria. In Agathis the Brachyoxylon type of pitting 

 persists for very numy years in the basal region of the seedling. It 

 has occurred to the writer that since the older less typically Araucarian 

 mode of pitting persists in the seedlings and cones of the living genera 

 of the Araucarian conifers, that the evanescent leaf traces, which are 

 likewise a feature of the Brachyoxylon type of wood as contrasted with 

 the persistent ones of the Araucarioxylon type, might be found in the 

 seedling axis of Agathis and Araucaria, in accordance with the general 

 biological law of recapitulation. An examination of the facts resulted 

 in a very gratifying realization of this theoretical expectation. Figure 

 b, Plate 8, shows a tangential section through the epicotyledonary 

 region of the seedling stem of Agathis australis, material of which was 

 obtained by Messrs. Eames and Sinnott, Sheldon Traveling Fellows 

 of Harvard University, on a journey to the Australasian region. In the 

 center of the figure are seen two leaf traces in transverse section. Of 

 these one is better developed than the other. The smaller one is 

 about to disappear. Figure c, Plate 8, shows a section of the same 

 stem a little farther out. The trace which shows smaller in Figure b, 

 has now completely disappeared and the persistent one has become 

 much reduced in size. A serial examination of sections showed that 

 the leaf trace came off as a single strand from the region of the pro- 

 toxylem of the stem and after passing out a very short distance divided 

 into two. The double strand thus produced is of \ery short duration 

 and finally disappears in both its divisions in the third or fourth annual 

 ring. As one passes up the seedling stem, the leaf traces are seen 

 to become more and more persistent until they reach a condition of 

 permanency like that characteristic of the older stem. It is clear 

 from the facts described that the leaf trace of Agathis, so far as .-1. 

 auairdlis is concerned at any rate, in the .seedling is an ev^anescent 

 structure and only becomes permanent later in life. The conditions 

 are comparable in fact mutatis mutandis, with the conditions found 



48 Hollick and Jeffrey, Coniferous Remains of Kreiseherville, Mem. N. Y. 

 Bot. Garden, 3. 



