x INTEODUCTION. 



specimens, which are also apparently intermediate 

 between them in other particulars. 



The time will come when a careful and minute 

 study of these insects in their different stages of 

 development will throw more light upon the subject, 

 and will probably lead to some useful revision of 

 their synonymy ; but it is difficult to foresee whether 

 such a revision will tend to increase or to diminish 

 the number of determined species in such genera as 

 those above referred to. 



Very few species of Pterophoridse have up to the 

 present time been recorded from North-west America. 

 Three were described by Mr. Packard in 1873, in the 

 'Annals of the Lyceum of Natural History, New 

 York,' vol. x. p. 266 &c., from California. 



Of these the first, Pterophorus perymcilidactylus, 

 is the well-known Pterophorus monodactylus of 

 Linne, as pointed out by Prof. Zeller (Verb. z.-b. 

 Ges. Wien, xxv. p. 266). 



The second, Pterophorus sulphureodactyhis, belongs 



