568 NATURAL SCIENCE. qct.. 



of the brain-case characteristic of these animals. The specimens 

 described by Dr. Deperet show, however, that this absence of ridges on 

 the skull is entirely due to the immaturity of Dr. Filhol's example ; and 

 the Edentate theory is, therefore, once for all demolished. On the 

 other hand, from the fact that the molar teeth of Chalicotherium and 

 Macrothenmn are extremely close to those of the extinct Perissodactyle 

 genus PalcBosyops, while many features in their osteology — especially 

 the transverse elongation of the head of the radius — are likewise of 

 an Ungulate type, Dr. Deperet comes to the conclusion that these 

 creatures were merely Perissodactyle Ungulates specially modified for 

 a fossorial, or possibly an arboreal, life. In this view we are entirely 

 disposed to concur, seeing that all the peculiar features of these 

 animals are just those which might have been produced by adaptation 

 for a particular purpose from an ordinary Perissodactyle Ungulate. 

 Still, however, it must be confessed that to find an Ungulate armed 

 with long curved claws, and furnished with disproportionately 

 elongated fore-limbs, like those of a sloth, comes as somewhat of a 

 shock to our ordinary preconceived ideas of an Ungulate. 



The second most interesting point in the memoir before us 

 relates to the gradual approximation to modern Pigs presented by 

 the molars of the later representatives of the extinct Oligocene and 

 Miocene animals known as Hyotherium. In the Oligocene representa- 

 tives of this genus (separated by Dr. Deperet as Palaochceriis), the 

 last molar has scarcely any hind talon ; but in the different varieties 

 of H. soemmcrringi of the Miocene the author finds such a gradual 

 increase in the length of this talon as to render it difficult to determine 

 where Hyotherium ends and Sus begins. 



The Quarternary History of the Baltic. 



Of late years, so much has been written on the Baltic and its 

 glaciation, that we are glad to welcome a summary of the present 

 state of our knowledge, especially when it is accompanied by a full 

 bibliography. 



In a paper of 120 pages, Herr Henr. Munthe deals with the 

 various Quarternary deposits of that region {Bihang till K. Svenska 

 Vet.-Ahad. Handl., band xviii., afd. ii., no. i). Following Professor 

 Nathorst, he divides the Quarternary period into five epochs : Post- 

 glacial, Younger Glacial, Inter-glacial, Older Glacial, and Pre-glacial. 

 Then, taking these epochs in regular order, he describes the deposits 

 and the fauna and flora which characterise each. As regards the 

 so-called "Pre-glacial" strata of the Baltic, we cannot help feeling 

 somewhat doubtful, for at present the list of fossils does not contain 

 a single characteristic " Pre-glacial " species, and it is not clear how the 

 fauna is to be distinguished from that of the "Inter-glacial" deposits. 

 The reindeer and dog {Cants faviiliaris, va.r. groenlandica), both unknown 

 in our Pre-glacial deposits, are the only land mammals of which the 



