458 



0. /.'. W/i/i/iit/ — WilUamsonian Tribe. 



It should be emphasized that the fossil fruit-yielding region 

 oi Oaxaca is large, extending into the State of Puebla, and 

 probably Guerrero, and the opportunities for opening quarries 

 almosl without limit. This is easily the most promising region 

 for the collection of Williamsonian types in North America, 

 and as already stated, ranks with the Yorkshire coast and the 

 Gondwanas of India, which it more nearly resembles, as the 

 third great region of the globe yielding an extensive William- 

 sonian fruit series. In a first season of collecting following 

 discovery by the writer, he secured along with a beautiful 

 Williamsonia series, Podozamites, Ptilop/iyUum, Otozamites 

 (or Pterozamites), Oycadolepis, Wielandiella (?) Araucari- 

 oxylon (silieified), Nceggerathiopais, Yuecites, Trigonocarpon, 



Fig. 15. ■ 



Fig. 15. Gnetales-like seeds of the Williamsonia-be&i-'mq horizon of 

 Oaxaca (^4.) compared with the seed of Gnetum gnemon (B), and Cycadeoidea. 

 4andBx]/2. Cx30±. 



(A) Portion of large slab from the Eio Mixtepec, Oaxaca, bearing three 

 leafy seeds with numerous small cycadaceous fronds and stem fragments all 

 thought to belong to one and the same plant. 



(B) Gnetum gnemon seed in superior view showing lateral leafy append- 

 ages or capsule like the preceding. 



(C) Cycadeoidea turrila seed in longitudinal section showing upper (radi- 

 cal) end of embryo, and structure of the apical region nearly paralleling 

 that of the similarly ribbed seed of Gnetum gnemon. The section traverses 

 two opposite wings of the outer or "blow-off" layer. 



Sphenopteris, Pecopteris, Cladophlebis (?), Taeniopteris, Glos- 

 sopteris, or Sagenopterids, Coniopteris (?) and Equisetum. 

 "Whence it is safe to say the Mixteca Alta region must fully 

 vie with, if not finally exceed both the Yorkshire coast and the 

 Gondwanas in the abundance of its Rhitt-Liassic plant life. 

 The flora is most like that of the Rajmahal Hills, and its 

 occurrence on the exact opposite side of the globe in precisely 

 the same latitude is, therefore, geographically impressive. 



