November 9, 1900.] 



SCIENCE. 



719 



not only add materially to the Museum 

 collections, but also throw additional light 

 on several of the many vexed questions re- 

 garding the structure and relationships of 

 the several genera of Dinosauria to which 

 the collections pertain. 



In addition to the work carried on in the 

 Jurassic, another field party, under the 

 immediate charge of the writer, operated 

 in the Laramie deposits of Converse County, 

 Wj'oming, and in the Tertiary of the same 

 region and in Sioux County, ITebraska. 



The early part of the season was devoted 

 to an exploration of the Laramie in the re- 

 gion immediately adjoining that which af- 

 forded the writer all the mammals and 

 most of the horned dinosaurs collected by 

 him under the direction of the late Pro- 

 fessor Marsh for the U. S. Geological Sur- 

 vey. The success that it was hoped might 

 reward an exploration of these deposits was 

 not entirely realized, though some impor- 

 tant material was obtained, including a 

 fairly representative series of Laramie 

 mammals and the other vertebrate remains 

 (fish, lizards, small dinosaurs, etc.) with 

 which they are always found associated. 

 One extremely interesting discovery in this 

 connection consists of a portion of a dental 

 plate with the teeth in position, of Plata- 

 codon nanus, described as a mammal by the 

 late Professor Marsh. The mammalian 

 nature of these remains has long been 

 doubted, our material showing the teeth 

 firmly ankylosed to the surface of the 

 dental plate demonstrates conclusively the 

 ichthyian nature of these teeth and that 

 Platacodon should now be removed from 

 the Mammalia to the Pisces. These re- 

 mains and others will be figured and fully 

 described by the writer in an article now 

 in course of preparation, which will be pub- 

 lished in the Museum Bidletin in the near 

 future. 



Among the more important dinosaurian 

 remains there is a considerable portion of 



the skeleton of Claosaurus, with some 25 

 or 30 vertebrae in position. This specimen 

 is believed to be unique among the known 

 remains of dinosaurs, in that there are pre- 

 served in it, in the region of the anterior 

 caudal vertebrse, an impression of the der- 

 mis which shows these animals to have been 

 enveloped in life with a covering of small 

 hexagonal plates or scales, something more 

 than one-half inch in diameter. This, I 

 believe, is the first accurate information we 

 have as to the nature of the dermal cover- 

 ing of dinosaurs. 



Late in July the Laramie was abandoned 

 and operations were commenced in the Daj- 

 monelix beds of the Upper Tertiary deposits 

 near Harrison, Nebr. These deposits, made 

 famous by Dr. E. H. Barbour of the Ne- 

 braska State University, are extremely rich 

 in the remains of these imposing and per- 

 plexing fossils. A very complete series of 

 Dtemonelix spirals and rhizomes were col- 

 lected, as well as important mammalian re- 

 mains from the same beds, and much valu- 

 able evidence secured, bearing directly upon 

 the different species and phylogeuy of Dse- 

 monelix and the conditions attending the 

 deposition of the beds in which the remains 

 are found. 



After some three or four weeks spent in 

 the Dsemonelix beds, our attention was 

 given to the underlying White River de- 

 posits. In these beds we were successful in 

 securing a nearly complete skeleton of Ti- 

 tanotherium in splendid condition, besides 

 many other animal remains of hardly less 

 importance. 



Of especial interest in connection with 

 these deposits was the discovery in the Ore- 

 odon beds of a thin layer of limestone, from 

 eight inches to a foot in thickness, contain- 

 ing in great abundance and in a beautiful 

 state of preservation the remains of mol- 

 lusca. Heretofore molluscan remains have 

 been extremely rare in the White .River, 

 and have usually consisted of only imper- 



