



1917] . CURRENT LITERATURE 247 



factors would give no indication of the condition of any of the original Swedish 

 biotypes, because plants having monomeric capsules occur normally just as 

 frequently as those having dimeric capsules in the offspring of the Fi and later 

 generations from such a cross. — Geo. H. Shull. 





Liassic flora of Mexico. — Wieland's 21 superb quarto memoir of 165 pages 

 and 50 plates has run the gauntlet of both the Mexican civil war and the world 

 war, since the Spanish text has been printed in Mexico and the illustrations 

 are from the famous lithographic firm of Werner and Winter of Frankfort. 

 The only internal evidence of this situation is the rather large number of 

 typographical errors in the Spanish text. The material was collected in the 

 province of Oaxaca in the southwestern Pacific region of Mexico. For the 

 most part it consists of impressions of leaves, and in a few instances fructifi- 

 cations of cycads or supposed Cycadophyta. Remains of Cordaitales are 

 described also from the formation w r hich is lowest Jurassic (Lias). One could 

 wish, however, that the evidence in the case of this group were somewhat 

 more definite, for it does not seem to establish definitely the presence of the 

 Cordaitales in the middle Mesozoic any more than the results of Lignier have 

 finally established the concurrent existence of Cordaitales and palms in the 

 Lias of France. Only structural evidence of an unquestionable character could 

 do this. One Arancarioxylon is described, but it differs from that genus in its 

 typical form by the possession of rays of more than a single layer of cells in 

 width. The memoir under review stands as one of the most important recent 

 documents of systematic paleobotany in regard to the Cycadophyta, and takes 

 its place with those of the same author on the extinct cycads of the United 

 States and those of Nathorst on the Cycadophyta of Yorkshire, England. 

 E. C. Jeffrey. 



Anatomy of Betulaceae.— Hoar 22 has investigated the anatomy of the 

 Betulaceae with reference to the phylogenetic position of the family. In the 

 Engler scheme, the family is placed among the most primitive Archichlamy- 

 deae, on the basis of flower structure. Since the most primitive family in the 

 Engler scheme is the Casuarinaceae, the genus Casuarina was included in the 

 investigation. The anatomy of the latter genus is either entirely primitive 

 or so generalized as to include both primitive and advanced characters, so that 

 its position near "the base of the dicotyledonous line" seems justified. The 

 Betulaceae possess the aggregate condition of rays indicative of a primitive 

 type, Alnus probably illustrating most completely the primitive condition of 

 the family. The more advanced genera (Carpinas, Ostrya, and Betula) have 



21 Wielaxd, G. R., La Flora Liasica de la Mixteca Alta. BoL Inst. Geol. Mexico, 

 no. 31. 1916. 





22 



Hoar, Carl S., The anatomy and phylogenetic position of the Betulaceae. 



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Amer. Jour. Bot. 3:415-435. pis. 16-19. 1916. 



