REVIEWS 615 



Tsinan Intrusive," by George B. Barbour; "The Constitution of Coal," 

 by Chung Yu Wang, in addition to numerous shorter papers and 

 abstracts. 



E. S. B. 



Revision of the Flora of the Green River Formation with Descriptions 

 of New Species. By F. H. Knowlton. United States 

 Geological Survey, Washington, Professional Paper 131-F, 

 1923. Pp. 133-76, pis. 36-40. 

 The Green River formation, formerly known as the Green River 

 shales, was named and described by F. V. Hayden in 1869. He recog- 

 nized it as being of purely fresh-water origin, and of middle Tertiary age. 

 Hayden showed full appreciation of its flora and fauna, and he under- 

 stood the great economic value of these shales for their oil contents. 



After dropping a number of names which had been formerly adopted 

 for the Green River flora by Lesquereux and others, Knowlton accepts a 

 list of plants among which the following groups are represented. There 

 are five well-marked fern types. No remains of conifers have been 

 reported, with the exception of some pollen grains. The monocotyledons 

 are better represen'-ed, and the best of all are the palms, of which there 

 are three nominal forms referred to different genera. Among the 

 dicotyledons are represented: 



Salix Ailanthus 



Myrica Rhus 



Juglans Sapindus 



Quercus Ilex 



Ficus Rhamnus 

 Brasenia 



Knowlton's inferences point toward a lowland flora which required 

 a climate that was at least warm, and possibly bordered on subtropical. 

 He also distinguishes an upland flora requiring unquestionably warm 

 and temperate climatic conditions. These deductions from the floral 

 elements are supported by the insect fauna of the Green River formation. 

 This fauna comprises a certain element that indicates tropical surround- 

 ings, and another that indicates cool, or perhaps temperate, conditions. 



A. C. N. 



