INTRODUCTION. 83 



fciin the habits and manners of such fishes as came 

 under our inspection, but likewise to secure, by- 

 faithful delineations, the appearance of their out- 

 ward forms and colours. 



How evanescent is that splendid hue, that change 

 of colour, which delights us so much if we see the 

 nimble fish near the surface of the water, and watch 

 its motions, — now darting forward, now wheeling 

 or assuming every posture between the horizontal 

 and perpendicular! To represent the variety of 

 , beautiful tints when in its natural element, is 

 a task as yet unaccomplished by the painters 

 brush. It has been my particular aim, that the 

 colours of those which were drawn, during our ex- 

 pedition, should come as near to nature as this 

 difficult task would permit. The first specimen of 

 any fish, a drawing of which we did not previously 

 possess, served generally to sketch its outward forms 

 and general colours on the paper; and when we 

 were fortunate enough to secure a second specimen, 

 those delicate hues were painted in, which are only 

 visible immediately after the fish comes out of the 

 water, and which so quickly vanish when life is 

 extinct. I found a most able coadjutor in Mr. 

 Vieth, who accompanied our expedition, and who 

 entered with the greatest enthusiasm in our ichthy- 

 ological researches. He has since fallen a martyr 

 to his researches, as a bite of one of the poisonous 

 snakes of Guiana, although inflicted many years 

 since, caused ultimately his death, in December 

 1839. 



