XVlll 
INTRODUCTION. 
upon themselves the task of describing and of superintending the 
delineation of the various specimens. Their contributions will form 
another 4to. volume of species entirely new, or, as before, of such as 
have been imperfectly described. The public in general are not aware 
how much is due to these gentlemen, without whose zeal and aid they 
would be deprived of much useful knowledge ; for, notwithstanding the 
liberal assistance of his Majesty’s government, there is so little encou- 
ragement for works of the above-mentioned description, that they 
could not be published unless the contributions were gratuitously 
offered to the publishers.. 
The extent and nature of the tables in the Appendix of the 
present work, and the necessity of revising all the computations since 
the return of the expedition, will account for the delay that has occurred 
in its publication. 
