24 BOTANICAL GAZETTE [JANUARY 
In the wood on the extreme right and left and radially nearer the 
right center, are seen dark patches, which on superficial examina- 
tion might appear to be the resin cells, characteristic of the wood 
of the Cupressineae and Taxodineae. An attentive microscopic 
examination of these, however, shows them to be clusters of 
black crystals of iron pyrites contained in the tracheids of the 
wood. 
Fig. 6 illustrates the structures of the wood as seen in longi- 
tudinal section. Toward the left can be seen the cells of the pith, 
while to the right of these can be made out the ringed and spiral 
elements of the primary wood. Further to the right, and occupy- 
ing over half of the field, is part of the secondary wood. The 
elements of the wood are narrow and are occupied by pits which 
in no case are contiguous or in more than a single row. With the 
restricted conception of araucarian woods which has prevailed 
almost until the present time, pitting of this character would not 
be regarded as indicative of araucarian affinities. As the result 
of recent investigations into the structure of mesozoic conifers, 
we now know that the wood genus Araucarioxylon Kraus does not 
cover all the araucarian ligneous types of the past. This genus is 
characterized by alternating or flattened pits on the radial walls 
of the tracheids, by smooth-walled ray cells, and incidentally by 
the absence of resin canals formed as a result of wounding. As has 
been pointed out by the present author in the memoir on the 
Kreischerville conifers and in other publications there cited, there 
are two other araucarian wood types in the Mesozoic, namely 
Brachyoxylon and Araucariopitys. In the former the pits are 
often of the flattened or alternating character found in the Araucari- 
oxylon type, but likewise are as often neither alternating nor 
flattened. Further, Brachyoxylon differs from Araucarioxylon 
in the formation of resin canals as the result of wounding, and 
resembles it in the possession of smooth-walled ray cells. Writers 
on cretaceous plants in general have failed to distinguish Brachy- 
oxylon from the Araucarioxylon type. In Araucariopitys we find, 
in addition to the pitting and wound reactions of Brachyoxylon, 
the strongly pitted ray cells which are characteristic of the Abie- 
tineae. This enumeration of araucarian woods, however, is not 
