79 

 CHAPTER XV. 



CLASSIFICATION OF MAMMALS. 



53. Order 1, Monotremata. The first order of 

 mammals is called Monotremata, and includes two 

 remarkable Australian forms, the platypus and the 

 spiny anteater. They are both small animals, being 

 about a foot in length. Both have long coracoid 

 bones separate from the shoulder-blade or scapula, 

 which, bird-like, reach as far as the sternum, and the 

 two collar-bones unite into a single T-shaped merry- 

 thought-like bone. In both forms there are two long 

 spur-like bones articulated to the front of the pelvis 

 and embedded in the abdominal muscles, and in 

 both the bones of the skull unite at an early period 

 to form a perfectly continuous braincase. They are 

 also characterised by the intestine and excretory 

 organs opening, as in the birds, into a common 

 cloaca (hence the name of the order). The platypus, 

 or Ornithorhynchus, is aquatic, and has a duck-like 

 bill and two small, flat, horny teeth in each jaw. The 

 male has a strong hollow spur on the ankle which 

 communicates with the duct of a poison gland and 

 is a weapon of offence. The spiny anteater, or 

 Echidna (fig. 36), is toothless, and has a long slender 

 horny bill, a worm-like tongue, and a dermal covering 

 of strong stout spines. The young of both these forms 

 are born in a very imperfect state of development 



54. Order 2, Marsupialia. The second order of 

 mammals is named Marsupialia, and includes kanga- 



