﻿8 INTRODUCTORY. 



These various facts coming to the knowledge of Prof. O. C. Marsh, of Yale 

 University, that famous scientist and collector — once a pupil of Goeppert — promptly 

 made every effort to secure extensive collections from the Black Hills ; and such 

 was his success that there are now in the Yale Museum, including the collections 

 subsequently made by the writer, more than seven hundred of these cycads from 

 the Black Hills alone. This immense collection, with various additional specimens 

 from elsewhere, is the most important in the world. In fact, it is doubtful if there 

 now are in all other museums put together so many well-preserved trunks as are 

 included in the Yale collection. Many of these trunks are figured and described 

 macroscopically by Ward in the Nineteenth Annual Report of the United States 

 Geological Survey (176), and in the American Journal of Science for November, 

 1900 (179). Most are from Minnekahta and Black Hawk, South Dakota, the two 

 localities which have yielded the most and the best-preserved fossil cycads known 

 to science. In addition to the cycads already recorded from these two localities the 

 writer should mention a collection of twenty specimens secured by him at Minne- 

 kahta for the American Museum of Natural History, New York, in the autumn of 

 1900 and spring of 1901.* During the same year the writer also secured for the 

 Yale collection, besides various other specimens, the remainder of the branches 

 completing the fine branching trunks shown on plates VII and x, as described in 

 Chapter II of the present volume. 



Cycads of the same species or genera and exhibiting the same characteristic 

 features of preservation as those from the main Minnekahta and Black Hawk local- 

 ities occur scatteringly at several other points of the "Rim," both east and west of 

 the Black Hills. It is thus evident that this picturesque mountain knot mantled 

 by the Permian, so strikingly like the Harzgebirge to the north of the Alps, is 

 girdled by the cycad-bearing horizon in which the Minnekahta and Black Hawk 

 trunks occur. Also, the writer found in a lower horizon on the western side of the 

 Hills, several miles south of Inyau Kara Mountain, a few specimens of Ward's genus 

 Cycadella. Numerous bones of large sauropodous dinosaurs accompanied these 

 specimens, and beyond doubt their horizon agrees with that of the cycads of the 

 Freezeout Hills, Wyoming, presently to be mentioned. Yale cycad 737, the type 

 of Ward's Cycadella (Cycadeoidea) utopiensis (179), is evidently from the same 

 horizon and general locality as these Inyan Kara Mountain specimens. This lower 

 cycad horizon likewise girdles the Black Hills, with the exception of a small south- 

 eastern segment, and appears extensively in a similar position and development in 

 the "Rims" of the Big Horn and other Rocky Mountain ranges. 



* These specimens are of considerable interest as including an unusual proportion of trunks bearing 

 very well preserved crowns of emergent young leaves, there being no less than six such among the twenty 

 trunks represented. The trunks were obtained chiefly from the eastern limits of the main Minnekahta 

 "cycad patch," and are not so dark in color as the specimens from farther west. Yale specimen No. 

 782, also secured by the writer from the same general locality as the American Museum cycads, and of 

 the same general appearance, bears a similar crown of young leaves. It is quite evident that this series 

 represents trunks derived from the same forest source at some vernal period of the year and silicined 

 under similar conditions. 



