INTRODUCTION. 67 



was observed still unattached, but in two hours it 

 had hold of the teat, and was actively employed 

 sucking.* 



An animal so little advanced as the young Mar- 

 supial at the time of its birth, requiring a constant 

 supply of food, and so ill fitted to bear the exposure 

 which the more advanced young of other animals are 

 subject to, must, it would appear, perish, unless some 

 peculiar provision for their safety were substituted, 

 and in the Marsupium or pouch, we find such a pro- 

 vision. This pouch, when the animal is very young, 

 has its orifice closed, and as it were glued to the 

 body of the parent, by a peculiar secretion. When 

 the young animal is more advanced, this secretion 

 disappears, and the young frequently leave the pouch 

 to return at will ; they do not entirely quit the pouch 

 until they have attained a large size that is, com- 

 pared with the parent. 



Closely connected with the pouch, and with the 

 generation of the animals of the present group, are 

 the Marsupial bones, which so peculiarly characterize 

 it. These bones are even more constant than the 

 pouch, being found in the Echidna and Ornithorhyn- 

 chus, in which no traces of a pouch have been dis- 

 covered. They are elongated and flattened, widely 

 separated at their distal extremity, and converge as 

 they approach the pubis, to which they are joined. 



The Marsupial bones, which are found in both 



* The mode by which the young Kangaroo reaches the 

 pouch immediately after birth is not yet known. 



