PREFACE. XI 



already affording ample occupation for a single 

 labourer. 



The catalogue of authors whose works have 

 furnished me with the principal facts detailed 

 in these volumes, is too long for insertion in 

 this place. I have not encumbered the pages 

 of the work by continual citations of authori- 

 ties ; but have given references to them only 

 when they appeared to be particularly re- 

 quisite, either as bearing testimony to facts 

 not generally knowai, or as pointing out 

 sources of more copious information. It may 

 however be proper to mention, that I have 

 more especially availed myself of the ample 

 materials on Comparative Anatomy and 

 Physiology contained in the works of Cuvier, 

 Blumenbach, Cams, Home, Meckel, De 

 Blainville, Latreille, and St. Hilaire, and in the 

 volumes of the Philosophical Transactions, of 

 the Memoires and Annales du Museum, and 

 of the Annales des Sciences Naturelles. I 

 should be ungrateful were I not also to ac- 

 knowledge the instruction I have derived from 

 my attendance on the lectures at the Royal 



