36 THE ZOOLOGIST. 



or pouched animals and distinguish them from the higher orders 

 of the placental mammals; laying particular stress, of course, 

 upon the absence of a placenta; upon the form and function 

 of the pouch as a receptacle for the young ; upon the imperfectly 

 developed condition of the young at birth ; upon the peculiar 

 modification of the breathing organs to prevent the danger 

 of choking by the forced injection of milk from the teat to which 

 it adheres ; and upon the relatively small size of the brain in 

 proportion to that of the head and body, with comparatively few 

 convolutions, indicating a low order of intelligence in these 

 animals. The marked peculiarity in regard to the succession 

 of the teeth is also referred to as characteristic of the Order. 



The Marsupials have adapted themselves to almost all modes 

 of life ; some, like the Thylacine (or so-called " Tasmanian 

 Wolf") running in the ordinary manner; some, like the 

 Kangaroos, progressing on the ground by long leaps ; others, 

 like the tree Kangaroos, arboreal ; others, again, like Phalangers, 

 volant, after the manner of Flying Squirrels ; while a single 

 species (Notoryctes) pursues a subterranean, Mole-like mode 

 of life. It is remarkable that, so far as is known at present, 

 there is no Australian Marsupial which is aquatic in its habits. 

 The reason for this, no doubt, is the fact that such a habit in a 

 pouched animal would be fatal to its existence, for unless it 

 periodically resided altogether on land, the young in the pouch 

 would be drowned by its immersion. The present state of 

 development in the Australian Marsupials, according to Mr. 

 Lydekker, is nothing to what it was during the Pleistocene or 

 latest geological epoch, for we find at that period evidence of the 

 existence of giant Kangaroos and Wombats (to say nothing 

 of extinct forms which have no living representatives), by the 

 side of which the largest existing species would appear almost 

 dwarfs ! The cause of this universal extinction of the most 

 gigantic mammals throughout the world soon after man had 

 made his appearance, is one of those problems which have not yet 

 received a satisfactory answer, for, as Mr. Lydekker remarks, not 

 even a glacial period could have made a clean sweep of the whole 

 globe. 



In regard to the present distribution of the Marsupials we 

 are disappointed at the paucity of information given in this 

 volume. We have searched in vain for statistics on several 



