PREFACE. vil 
niary acquisition, [ have, though not without con- 
siderable hesitation, undertaken this work. 
That it will be attended with extraordinary dif- 
ficulties on the part of the author must be evident. 
Acting the part of a pioneer in an untried path— 
destitute of a colleague with whom to consult in 
case of doubt—without the proximity of extensive 
and well arranged cabinets, and, more particularly, 
with but few books for reference, [ am constrained 
to rely solely on my own exertions, with the reso- 
lution that nothing on my part shall be wanting 
that zeal can supply or industry accomplish. 
Nevertheless, I cordially invite the co-operation 
of those friends of science who have attended to 
this subject; their discoveries will be scrupulously 
acknowledged and registered, and of the speci- 
mens they think proper to communicate, such as 
are new to me will be gratefully placed to the cre- 
dit of the discoverer. 
As to the plan upon which this work will be 
conducted, it may not be improper to remark, in 
this place, that the celebrated publication of Mr 
