OEDEE OF MONOTEEMATA. 
11 
delphes, wishing to show by this name that the reproductive 
organs of these Mammalia, and the manner in which they accom- 
plish their generative functions, remind one, in different ways, of 
what passes among birds. However, this expression was never 
adopted, and we will preserve the first denomination, so as to 
comply with what is usually accepted. 
The Monotremata resemble birds again in their mouth, which 
is toothless, and which terminates in a sort of horny beak, of a 
rather singular form. 
They are like reptiles as far as the form of the shoulder is 
concerned, for it presents, as in the Saurians (Lizards and Cro- 
codiles), a double clavicle or collar-bone. 
In all other respects they are true Mammalia. They have 
mammae, very rudimentary indeed, but which secrete a milky 
fluid, destined to nourish their young. These glands are deprived 
of externally visible udders and are consequently scarcely notice- 
able, which explains how for a long time there were some who 
denied their existence. The Monotremata are provided with four 
unguiculated members ; their bodies are covered with hair, and 
they have marsupial bones, like the animals which compose the 
second order of Mammalia, although these bones, in their case, do 
not support the pouch which is the distinguishing feature of the 
latter. 
Much discussion has taken place on the question as to whether 
the Monotremata are oviparous or viviparous. It has been well 
proved now that they give birth to their young alive ; but it 
cannot be doubted that their mode of gestation differs greatly 
from that of the ordinary viviparous animals. All naturalists agree 
in saying that in this respect they resemble much the ovo-viviparous 
Vertebrata, that is to say, those in which the egg is hatched in 
the mother’s body, by interior and direct incubation ; such are 
the Yiper among reptiles, and, among fishes, some of the Hay and 
Shark tribe. 
Only two families of Monotremata are at present known : viz. the 
Duckbill ( Ornithorhynchus ) and the Porcupine Ant-eater [Echidna). 
The discovery of these strange animals only dates back as far as 
the year 1722. The Ornithorhynchus and the Echidna inhabit 
exclusively Tasmania (or Yan Diemen’s Land) and Australia, that 
country so remarkable for the singularity of its fauna, and in 
