26 EVOLUTION OF LIFE. 
forms, such as the Flying Lemur. There are many similar 
examples: the Aye-Aye (Cheiromys) has teeth like a rat, 
while in other respects it is a monkey. The Duck-bill 
Platypus of Australia (Ornithorhynchus) combines the 
organization of lizard in its breast-bone, crocodile in its 
ribs, and bird in the skull and digestive apparatus, and yet 
is a four-footed animal. 
KINGDOM INTERMEDIATE BETWEEN ANIMALS AND PLANTS. 
In modern times, through the assistance of the micro- 
scope, many minute beings have been discovered which 
have been successively classified as plants or animals, 
according to the botanical or zoological tendencies of their 
describers. As these microscopic beings present the life of 
both plant and animal at different stages of their existence, 
it is quite impossible to say to which kingdom they belong. 
Many naturalists are, therefore, agreed to consider them as 
a something apart, an intermediate original kingdom, out 
of which the plant and the animal worlds have been evolved. 
If life has been gradually developed, and there has been a 
progress from beings of low organization to higher, it is 
natural that such a kingdom should exist, partaking in 
its nature of animal and plant characters. The origin of 
life is to be sought, therefore, in this main root, of which 
animals and plants are the rising diverging branches. The 
beings of this animal-plant kingdom* which still exist are 
only the descendants of a larger kingdom long since extinct, 
or perhaps some of the most simple are still formed through 
spontaneous generation. 
* The limits of this essay permit the noticing of only a few of the orders 
of the intermediate kingdom. 
