10 PREFACE. 



The materials I have employed in constructing* this 

 little treatise are derived principally from my own 

 practical observations^ although 1 am free to ac- 

 knov\^ledge that I am greatly indebted to Miilier and 

 Ehrenberg, especially for the arrangement of them : 

 and as this department of zoology is mainly dependent 

 on the plates for affording any thing like a compre- 

 hensive view^ of it, immense pains have been taken 

 to give the numerous drawings as nearly as possible 

 the appearance of what they are intended to repre- 

 sent, when viewed under the microscope. Where 

 the details^ as in many instances^ cannot be ad- 

 mitted^ stilly on the whole^ a great similarity is pre- 

 served. Mr. Cleghorn has shewn much talent in 

 the Engravings, some of which^ I may safely say, 

 in point of execution can hardly be excelled. 



ANDREW PRITCHARD. 



18^ Picket-Street, London. 



