THE ROYAL NATURAL HISTORY. 



INVEBTEBBATE ANIMALS. 



CHAPTER I. 



The Jointed Animals, — Subkingdom ARTHROPODA. 



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 

 subkingcloms 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 



VOL. VI. — I 



