vi INTKODUCTION. 



assistant Thomas Eedle, to capture and set a great 

 number of specimens nearly every day, and to bring 

 them to Europe in the best possible condition. 



One large tin case, divided into about seventy 

 partitions, was exclusively devoted to the rearing of 

 Microlepidoptera from their earlier stages, in as many 

 wide-mouthed glass bottles, which were corked or 

 covered with wire gauze, according to the circum- 

 stances of each particular case; but, although this 

 enabled me to ascertain the food-plants of many 

 interesting species, I unfortunately omitted to make 

 any sufficient descriptions or to preserve specimens of 

 the larvae. 



The numerous species of Pterophoridae forming so 

 great a proportion in the rich results of this expedi- 

 tion prove that that group is strongly represented in 

 the Western States, and that the close resemblance to 

 European forms, which has so often been mentioned 

 by different writers as one of the characteristics of the 

 Lepidopterous Fauna of Western North America, is 

 here fully maintained. 



