ADVERTISEMENT. 



The present Volume is not a reprint of that on the same 

 subject, published in 1843. The difference between them 

 is in some measure indicative of the progress of the anatomy 

 and physiology of the Invertebrate Animals, during the ten 

 years which intervened between my first and last course of 

 Lectures on that subject. 



My friend and former pupil, Mr. W. White Cooper, having 

 published his notes of the Lectures of 1843, in numbers, as 

 they were delivered, time was not allowed to add references to 

 the original authorities for many of the facts and opinions 

 quoted in those Lectures : in the present Work, I have 

 endeavoured to supply that omission according to the plan 

 adopted in the volume on the Anatomy of Fishes : and some 

 additions have been made of contributions to Invertebrate 

 Anatomy and Physiology up to the date of publication. 



Royal College of Surgeons, London, 

 May, 1855. 



