237 



talia of particular value in the determination of the specific identity or 

 non-identity of closely allied forms in different continents or faunal 

 areas, and of the various forms in species, which exhibit great variety 

 in color and wing pattern. Differences of opinion as to the identity or 

 non-identity of such forms may at once be changed from individual 

 speculation to scientific certainty by a comparison of the male genitalia 

 of the forms in question. The structure of the male genitalia is nor- 

 mally too intricate for successful photographic reproduction and really 

 satisfactory figures must be drawn under the specialists' close super- 

 vision ; but in very many cases can the species be definitely recognized 

 from a good photograph of its male genitalia alone and it has been 

 deemed worth while to so illustrate in this paper examples of various 

 forms in the different micro-families in the hope to stimulate further 

 study and more perfect illustration of these absorbingly interesting 

 organs, which will give much new light and aid to the proper classifi- 

 cation of the Microlepidoptera. 



We like to call attention to the fact that Lord Walsingham first 

 used these organs for specific differentiation in the present family 

 thirty years ago (Insect Life, Vol. II, 1889) and that his few simple 

 genitalia characters then given for his new species in the genus 

 Stenoma enable their recognition. 



Incidentally it may be stated that the genus Mcncsta Clemens, 

 which Walsingham at that time considered allied to Stenoma and the 

 relationship of which has since been in dispute and of some uncer- 

 tainty, due to the reduced and superficially Stcnomid-Wkt venation, is 

 conclusively proven by its genitalia not to be a Stenomid but a Gelechid. 



Only two genera of this family is at present recognized from 

 North America north of Mexico ; they may be separated as follows : 

 Forewings with 11 veins; 2 and 3 coincident: Hindwings, with 7 veins; 



3 and 4 coincident Mcitcsloinorpha Walsingham 



Forewings with 12 veins; Hindwings witli 8 veins Stenoma Zeller 



Genus Menestomorph.\ Walsingham. 



1907, Proc. U. -S. Nat. Museum, \"ol. NNXIII, p. 214. 



Type : :!/. oblongata Wlsm. 



Forewings with 11 veins; 7 to apex; 2 and .3 coincident, stalked 

 with 4. Hindwings with 7 veins ; 3 and 4 coincident, connate with 5. 



Only one species is at present recognized. 



