G. R. Wieland — Williamsonian Tribe. 



439 



In addition the Oaxacau localities yield three other stem 

 types presumably all generically distinct, one being nearly like 

 the Williamsonia forms of the Yorkshire coast, one a heavy 

 columnar type, and the third slender branching forms presuma- 

 bly more like Wielandiella, accompanied by small Otozamites 

 leaves in an association leaving slight doubt that an entire plant 

 is represented. 



Fig. 3. 



Fig. 3. Williamsonia sp. x 1/3 nearly. 



A branching, scale-leaf covered stem, or possibly stem and peduncle, on a 

 slab bearing fragmentary cycad and other foliage. (Cliffs of Hawkser and 

 Eunswick, 1843 or earlier. James Yates Coll.). 



To this general evidence there can be added bnt two 

 recorded instances of organic union of stem and leaves, — the 

 Gondwana stem with heavy concentric wood rings, noted by 

 Seward as having Ptilqphyllum cutchense leaves attached, and 

 the famous stem of the Paris Museum Yates collection with 

 Zainites gigas fronds attached, as figured by the writer several 

 years ago (20). But save these general facts gleaned from 

 evidence of association as borne out by rare instances of 

 organic connection, and not once clearly extending to struc- 

 ture, all direct knowledge of Williamsonian stems suddenly 

 stops and stubbornly awaits the discovery of silicified forms, or 

 at least the elaboration of some better carbonized parts than have 

 so far been seen. Such in the hands of some shrewd worker 

 using the Nathorst collodion-method, or the Hollick and 

 Jeffrey staining and imbedding method, may perhaps suffice. 



