TRIP TO THE YELLOW STONE. 207 



difficulties that stood in the way : with his ex- 

 perience, and with his usual energy to help him, 

 bending his mind to the task he had thus taken 

 up, he at once began to arrange his plans, and 

 having decided to bring out the work in a size 

 sufficient to give figures of all the animals 

 not larger than the raccoon, of their natural 

 dimensions ; he soon was deeply engaged in 

 preparing it. 



He was aided in this arduous task, not only 

 by Dr. Bachman, but by his sons, V. G. and 

 J. W. Audubon, the former painting the back- 

 grounds, drawings of trees, plants, etc., and 

 editing the manuscript for the press, and the 

 latter procuring and drawing some of the ani- 

 mals in Texas, California and elsewhere. 



Audubon was also assisted by hosts of friends, 

 many of whom are named in the introduction 

 to the work, including Sir George Simpson, of 

 the Hudson's Bay Company, the Chouteaus, of 

 the American Fur Company, etc., etc. This 

 work involved the necessity of further journey- 

 ings, and among the rest, a trip to the Yellow 

 Stone river and the spurs of the Rocky Moun- 

 tains, which expedition was made in IS-iS, and 

 was productive, besides its results in respect to 

 the history of the quadrupeds, of further dis- 

 coveries in ornithology, some twenty new 

 epecies of birds having been added by it to the 



