﻿FOLIAGE. 



85 



putting forth its energies in the unfolding of an additional series of leaves. Hap- 

 pening to be fossilized at such a critical time in its life under the most favorable 

 conditions, there thus came to be preserved a wealth of characters, scarcely rivaled 

 by any Mesozoic plant of which there is a record. This specimen alone affords 

 material for a restoration. 



The first searching examination 

 of this wonderful trunk showed 

 that, as found in the field, it had 

 been subjected to the erosive action 

 of sand-laden winds on the hillside 



A B 



Fig. 47. — Prefoliation and frond emergence of existing cycads. Type II. 



A. Zamia floridana. X 3- Summits of three trunks (a, b, c), with all old fronds wilted down, and showing only 

 the young fronds of semi-fern- like habit of emergence, in which the pinnules lie straight and the rachis is once 

 deflated. Rachial elongation mainly precedes pinnule growth. (Author's plants.) 



B. Zamia Lindeni. X J. Armorless type of cycadean trunk bearing two emergent young fronds, the petioles of 

 which are fully elongated, while the rachis is yet short and the straight-ranked pinnules minute, although clearly to 

 be seen in the figure. The slight inward curvature of the young rachis shows that it was earlier once deflexed, as 

 in A. (Conservatory of Miss Helen Gould, Tarrytown-on-the-Hudson.) 



where it lay, and that oeolian polishing had partially exposed, in exquisitely clear 

 transverse section, the tips of two adjacent young leaves plainly belonging to the 

 normal helicoidal series and just ready to emerge at a distance of about 5 to 8 cm. 

 from the apex of the trunk. Several pairs of these leaves as enveloped in ramen- 

 tum were removed for study, and the disposition of their parts with reference to the 

 trunk determined from the requisite sections. 



