Prof. K. A. von ZittelL—On the Mammaha. 459 
those of Pleistocene and living genera. According to Ameghino 
even two existing genera (Dasypus and Chlamydotherium) make their 
appearance in the Santa Cruz formation. The Edentates cannot, 
therefore, be appealed to as witnesses for the ancient character of 
the fauna. Just as little can the Rodents. These also belong 
exclusively to Hystricomorphous forms of a specifically South 
American stamp, and they are in part very closely connected with 
genera still living or even altogether identical with them (as 
Lagostomus). heir supposed relations to the Huropean Protrogo- 
morpha (Theridomys, Nesokerodon, Archeomys) have proved deceptive, 
and the same is also the case with regard to the North American 
Tertiary Rodents. The mostly high prismatic teeth and the absence 
of a milk dentition are proofs that the Rodents of the Santa Cruz 
formation have on the whole reached a higher grade of develop- 
ment than their Upper Hocene relatives in Hurope and North 
America. Amongst the Toxodonts only the Homalodontotheride 
show primitive features; all the rest have a highly differentiated 
dentition, mostly prismatic molars and reduced extremities. In 
the Typotheria the generally closed rows of teeth and the five-toed 
extremities betray a more primitive condition than in their suc- 
cessors of the Newer Tertiary and of the Pampas formation, but 
even in this group the curved molars have already reached a 
prismatic form. Finally, the Apes can in no wise be considered as 
the stock from which all our present Simiz have descended, for they 
have a definite South American stamp, and, as regards differentia- 
tion, they stand markedly above the more generalised Pachylemuridee 
of the European and North American Tertiaries. 
Taken all in all, the Santa Cruz fauna has distinctly reached a 
higher rank than the mammalian groups in the Lower and Middle 
Hocene of the Northern hemisphere. It can, at the furthest, be placed 
on a parallel with the Upper Hocene or with the Oligocene of Hurope. 
OLIGOCENE. 
The coal-bearing Lower fresh-water Molasse of the North and 
South Alps (Upper Bavaria, Switzerland, near Vicenza, Cadibona 
and Zovencedo in Liguria) and of the Waadtlander highlands 
(Rochette, near Lausanne) ; the contemporaneous deposits in Hun- 
gary (Gran) and Dalmatia (Monte Promina) ; the marine sands and 
brackish marls of the Mayence basin; of the Upper Rhine valley 
(Lobsann) ; of the neighbourhood of Paris (Fontainebleau, Etampes); 
the fresh-water marl of Ronzon near Le Puy, Villebramar, St. Henri, 
Manosque, and other places in the South of France, and the lacustrine 
deposits of Hempstead and Colwell Bay in the Isie of Wight, contain 
a scanty mammalian fauna composed of the following genera :— 
MARSUPIALIA. ARTIODACTYLA. RODENTIA. 
Didelphys. Anthracotherium. Theridomys. 
Amphiperatherium. Ancodus. Cricetodon. 
» Elotherium. 2? Decticus. 
PERISSODACTYLA. Plesiomeryx. ? Llomys. 
Aceratherium. Gelocus. 
? Ronzotherium. 
