VI 
PREFACE. 
under investigation without a direct acquaintance with them. 
It is indeed desirable that the author of a work of this kind 
should have examined all the species, and in various distant lo- 
calities, that he may justly characterize them, and estimate the 
extent of their variations ; nor was the circumstance of the com- 
parative unmoveableness to which a medical practitioner is 
doomed unconsidered as a bar to my own competency, but the 
love of the subject prevailed, especially when friends were readi- 
ly found to contribute to the removal of the difficulty. To 
them I have in this place to render my grateful acknowledge- 
ments. To Mr Bean of Scarborough, Dr Coldstream of Leith, 
J. V. Thompson, Esq. Inspector of Hospitals, for some time 
resident in Cork, and the Rev. David Landsborough of Ste- 
venston in Ayrshire, I stand indebted for numerous specimens ; 
and similar communications of less extent have been sent me 
in a friendly manner by John Edward Gray, Esq. of the British 
Museum ; Mr Robert Embleton, surgeon in Embleton ; Messrs 
Alder and Bowman of Newcastle; Mr Teale of Leeds : J. Hogg, 
Esq. of Norton ; and Messrs Macgillivray and P. W. Mac- 
lagan of Edinburgh. One other name must not be forgotten, 
for, besides a friendly interest in the book, and his revision of it 
during its progress through the press, I have had the kind as- 
sistance of the Rev. Thomas Riddell, of Trinity College, Cam- 
bridge, whenever the assistance of a classical scholar was re- 
quired. 
I am not certain that any apology will be deemed necessary 
for the notes and quotations which have been introduced with 
considerable liberality, for the tastes of the naturalist have 
ever seemed to me akin to those of the antiquary ; and this has 
always been a favourite mode of illustration with the latter. It 
is one that chimes in with my own humour, and the indulgence 
of it seemed at least harmless on the present occasion. Many 
of these notes are devoted to notices of the individuals who, 
so far as I could learn, were the first to notice the species of 
