PREFACE. Xlll 



latter is comparatively valueless to the former. Hence many topics of 

 great scientific interest are entirely passed over; and it is hoped that 

 such omissions will not be accounted as faults in the estimation of those, 

 who dread lest the attention of the Student should be too much drawn off' 

 by the seducing novelties of Science, from his less attractive, but more 

 important objects. 



For a large part of his illustrations, the Author is indebted to the 

 valuable and beautiful Icones Physiologies of Prof. Wagner. He has 

 indicated the sources of all which are not original. 



In conclusion, the Author would repeat what he has already had oc- 

 casion to state;- that in a work involving many details, it is not to be 

 expected that no error should have crept in; but that he has endeavoured 

 to secure correctness, by relying only upon such authorities as appeared 

 to him competent, and by comparing their statements with such general 

 principles as he considers well established. For the truth of those 

 principles, he holds himself responsible ; for the correctness of the details, 

 he must appeal to those from whom they are derived, and to whom he 

 has generally referred. He hopes that he will not be found unwilling to 

 modify either, when they have been proved to be erroneous ; nor indis- 

 posed to profit by criticism, when administered in a friendly spirit. 



Bristol, Feb. I, 1842- 



