PALEONTOLOGY. 423 



a richly diversified micro-fauna of mammals in the Upper 

 Jurassic deposits, and a similar fauna in the youngest Creta- 

 ceous horizons of Wyoming and Colorado. A monograph, 

 with plates of very high excellence, was devoted by Marsh 

 (1884) to the description of the gigantic Dinocerati, which 

 form a group of fossil Mammalia peculiar to North America. 

 A large number of memoirs by Marsh appeared in successive 

 publications of the American Journal of Sciences, and made 

 known the important results of his researches on the interest- 

 ing faunas of the Far West. 



Contemporaneously with Marsh, his indefatigable rival, Cope, 

 also worked at the fossil Mammals of the Western States. 

 Unfortunately these two highly-gifted palaeontologists were 

 not on friendly terms, and it frequently happened that their 

 works on special genera and species overlapped. Cope's 

 greatest interests were systematic, and he made several im- 

 provements in the classification of the higher Mammals. His 

 two reports on the extinct Vertebrates in New Mexico (1874) 

 and on the Vertebrates of the Tertiary formations in the 

 Western States (1884) contain an extraordinary wealth of new 

 observations. Cope discovered a new fauna in the so-called 

 Puerco formation, the oldest horizon of the American Eocene 

 deposits. 



Cope's work comprised the fossil Mammalian remains found 

 in Mexico, Central America, and the West Indies. In Brazil, 

 a Danish geologist, P. W. Lund, discovered and described 

 (1841-45) a diversified fossil Cave Fauna. The wide Pampas 

 in the Argentine, in Uruguay and Paraguay, proved to be a 

 rich field for the remarkable fossil Edentate forms. The 

 osteological characters of the gigantic fossil Sloths found 

 abundantly here and in the Pleistocene deposits of other parts 

 of North and South America have been investigated by Owen, 

 Gervais, D'Alton, Huxley, Flower, Nodot, H. von Meyer, and 

 more recently by H. Burmeister (1864-81), J Reinhardt 

 (1875), and Florentine Ameghino. 



Next to the discoveries of Mammalian faunas in the west of 

 North America, the most important palseontological event of the 

 two last decades of the nineteenth century has been the disclo- 

 sure made by Florentine Ameghino of a rich Mammalian fauna 

 in the Tertiary rocks of Patagonia. New forms are constantly 

 being added from the inexhaustible fossil localities in the pro- 

 vince of Santa Cruz. The fauna is being described entirely by 



