282 



understand that the collection contains ])aratypes of others, but since 

 we have not examined these we prefer to reserve comment upon them. 



In the British Museum are the types of the few species which 

 Walker described from this continent, in addition to Lord Walsing- 

 liam's collection, which contains his own types and some of Zeller's. 

 Mr. Meyrick has very kindly visited the Museum in our behalf and 

 compared specimens with all of these types. We are indebted to him 

 also for making comparisons with the types in his own collection, and 

 for the gift of a paratype of Ptcrophorus citrites, which we had been 

 unable to place. 



These comparisons have enabled us to establish beyond doubt the 

 identity of all species occurring in North America, with the exception 

 of those described in Europe by the older writers, Linnaeus, Haworth, 

 Huebner, and Denis and Schiffermuller, and a very few whose types 

 we have not located. I'^ortunately the latter class includes only two or 

 three species about which there can be no reasonable doubt. 



We wish to express our gratitude to those men whose assistance, 

 either privately or as the officials of museums, has enabled us to lay 

 a foundation of such gratifying soundness for our revision. 



In the preparation of the paper we have concluded to illustrate 

 only the primaries of the insects, solely for the reason that it is im- 

 possible to secure sufficient magnification of an entire specimen and 

 at the same time retain such depth of focus as is necessary to produce 

 a photograph with satisfactory definition. In the case of Trichoptiliis, 

 PteropJwrus, Platyptilia, and the few species of other genera whose 

 secondaries show characters of specific value, we illustrate these wings 

 as well, but we have been forced to omit the bodies, even though in 

 a number of species they are very distinctively marked. The illus- 

 tration of genitalia has also been curtailed as much as possible, but 

 we are able to give notes or a figure of at least part of the genitalia 

 of all species except T. pygmaeus Wlsm., P. wilUamsi Grin., rhodo- 

 dactyla D. & S., xylopsamma Meyr., 0. baroni ¥\s\\, citrites Meyr. 

 and iiiiicolor B. & McD. The value of the genitalia is limited, and 

 in many cases where we have made a figure from a single slide we 

 cannot say that the figure will be more than a possible help in the 

 identification of the species. 



In the figures of genitalia will be found some points which may 

 need explanation. We have drawn these structures as opaque objects. 



