LETTER TO THE SECRETARY. 



Washington, November 1, 1883. 



Sir: I have the honor to transmit, for your approval, the eighth vol- 

 ume of the final reports of the United States Geological and Geographical 

 Survey of the Territories, prepared by the eminent paleontologist, Prof. 

 Leo Lesquereux. 



A brief synopsis of the contents of the volume may be given as 

 follows : 



In the first part— the Cretaceous Flora— are described a large number 

 of new species, some representing rare and very remarkable types, all of 

 which are figured on the first seventeen plates. Besides the description 

 of the species, there are some general remarks on the geology of the 

 Dakota group, and on the character of the plants in regard to climate and 

 their affinities with plants of succeeding geological periods. A table of 

 distribution is added, enumerating all the species known up to the present 

 time, pointing out the relations of the plants of Europe and various parts 

 of North America with those of the Dakota group in Nebraska, Kansas, 

 and Colorado. The number of species enumerated in this table is 443, 

 of which 200 are from the Dakota group. 



The second part contains a revision of the plants of the Laramie 

 group. The introduction considers the relations of these plants to those 

 of Europe, for the purpose of fixing the age of the formation. Then 

 follows a description of a few new species from very fine specimens on 

 three plates, and a table of distribution including only the species of the 

 Laramie group, which in the seventh volume of the series were mixed 

 with those of the other stages of the Tertiary and were not grouped clearly 

 enough for the proper appreciation of the general characters of the flora. 



Up to the present time the author has been unable to find a single 

 species that he could identify with any from the Dakota group. He has 

 now in his possession very large collections of plants from this group, 

 which have not been reported upon, collected in Colorado and Wyoming; 

 yet after a careful examination he fails to find any form even related to 

 those of the Dakota group. 



The third part reviews the flora of the White and Green River regions, 

 which he separates into two groups. The plants of Green River and Alkali 



