X PREFACE. 



modern science are new, and custom lias so 

 generally affixed to these new ideas classical 

 expressions, that it would be both absurd and often 

 unintelligible to substitute homelier expressions 

 for them — to exchange, for example, such words as 

 thorax, abdomen, oval, for chest, belly, egg-shaped / 

 that others, as homogeneous, parasitic, truncate, &c. 

 can be otherwise expressed only by using many 

 words ; and that not a few, as cilia, tentacle, 

 antenna?, have really no correspondent Avords in 

 Saxon English. 



I have, however, added a glossary for the ex- 

 planation of such technical terms as were unavoid- 

 able ; or else have taken care to expound them on 

 their first occurrence. With these aids I trust 

 there is not an expression in the book which 

 a person of average English education will not 

 understand. 



But what I consider the principal feature of this 

 work is the copiousness and character of its illus- 

 tration. Perhaps I may say that I have enjoyed 

 more than ordinary facilities for a labour of this 

 kind. Having been accustomed from childhood 

 to draw animals from the life, I have accumulated 

 in my portfolios about three thousand figures of 

 animals or parts of animals, all drawn by myself 

 from nature, of which about two thousand five 

 hundred are of the Invertebrate Classes, and about 

 half of these done under the microscope. The 



