THE ROYAL NATURAL HISTORY 
INVERTEBRATE ANIMALS. 
CHAPTER I. 
The Jointed Animals,— Subkingdom ARTHROPOD A. 
The Insects,— Class Insecta. 
Ants, Wasps, Bees, etc.,— Order Hymenoptera. 
,. .. . In the early days of zoological science, when the value in classification 
Distinction J J 
between Verte- of the structural and embryological characters of living beings was 
brates and in- but little understood, the animal kingdom was divided into two 
subkingdoms called Vertebrata and Invertebrata; the former embrac¬ 
ing those forms provided with a vertebral column, or backbone, and the latter those 
that were not so provided. With the addition of some few classes, whose organ¬ 
isation has only recently been fully comprehended, the Chordata of to-day are 
coextensive with the Vertebrata of half a century ago. But the term Invertebrata, 
as denoting a natural assemblage of animals, has long ceased to be used by every 
competent zoologist, and is nowadays merely applied as a conveniently vague title 
for all the animals that have not acquired the characters of the Chordata. This 
change of opinion has been brought about by the attainment of a far more intimate 
acquaintance with the structure and development of the lower animals than our 
predecessors, with their less refined methods of investigation, could possibly 
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