DEPARTMENT OF FOSSIL PLANTS. 189 



placed on a basis that will admit of its extensive geological use. Prof. 

 Knowlton also identified and revised, by the aid of Museum material, 

 a considerable collection of plants from the Bozeman (Montana) coal 

 field and prepared a report which will soon be printed. It enumerates 

 forty-four species, five of which are described as new to science. 



The accessions of Upper Paleozoic material, with the exception of the 

 fossil woods, have been examined by Mr. David White, who has reported 

 on all minor transmittals. In connection with his regular survey work 

 Mr. White has also spent a considerable time on the collections sent by 

 Dr. J. H. Britts from the tower coal measures of Missouri, and the first 

 collection forwarded by L. Graff from Van Buren, Ark., the speci- 

 mens being studied by genera, together with those of the Carboniferous 

 plant collections of the II. S. Geological Survey now in his hands. The 

 work on the Britts collections, which include a number of new or little 

 known forms, will probably be completed by the 1st of January. His 

 study and other work on the Lacoe collection is mentioned in the part 

 of this report relating to that particular collection. 



Mr. Charles S. Prosser was in the field from July 1 to August 26, 

 engaged in studying the Middle and Upper Devonian formations of 

 Monroe, Pike, and Wayne Counties, Pa., with special reference to the 

 flora and fauna. The collection made is of great importance in deter- 

 mining doubtful horizons and correcting previous errors. His time in 

 the office was largely spent on the compendium of paleobotany which 

 has been in preparation for some years in this office. 



An entirely new arrangement of the exhibition series of fossil plants 

 was begun. Heretofore the plants had been arranged systematically, 

 with a view to illustrating, as far as the material admitted, the origin 

 and development of plant life, but it had been found that plants widely 

 separated geologically were brought side by side, and it was thought 

 best to abolish the botanical and substitute for it the geological ar- 

 rangement. Each plan of arrangement has its advantages, but as all 

 the other paleontological collections were arranged geologically it 

 seemed as well to have the plants conform. The system of placing 

 each specimen on an ebonized block was also abandoned as unsatisfac- 

 tory. 



As the exhibition series is confined to a single row of table cases in 

 the fossil court, nothing like a complete series can be shown, but 

 beginning with the lowest plant-bearing rocks, enough specimens were 

 placed on exhibition to give a fairly good idea of the predominant 

 vegetation of each period. The specimens illustrating the Devonian, 

 a part of the Carboniferous, and all of the Potomac were put in the 

 cases. The last-named flora, that of the Potomac, is very fully exhib- 

 ited on account of its peculiar types of vegetation. The other forma- 

 tions will be as fully illustrated as the space will admit. 



The flora of the Dakota Group, by the late Prof. Leo Lesquereux, 

 as announced in the last annual report, was printed during the year. 



