274 AMERICAN MICRO- LEPIDOPTERA. 



apex sometimes contains a well-defined, regularly shaped black dot, 

 formed of closely overlapping scales. In other species, these scales 

 are more or less scattered. 



In the synoptic table, and as a factor in the sequence of the spe- 

 cies, the use of the term "apical spot" or "apical dot" has been 

 restricted to those species in which the apical dot is circular or 

 nearly so, and is not connected with a streak of scattered scales ex- 

 tending along the middle of the wing before the apex. L.fitchella 

 and L. lucidicostella possess typical apical dots. Typically, this dot 

 is placed at the apex of the wing membrane. In intermediate 

 forms, such as morrisella, uhlerella, gemmea, the apical spot may be 

 so increased in size as to occupy the entire apical portion of the 

 wing. 



The white costal and dorsal streaks occupy the interspaces be- 

 tween the veins. The veins then, within certain variable limits, 

 determine the position of these marks. The first costal streak is 

 placed beyond vein 12, and is the most variable in position ; the 

 second just before 11 ; the third between 11 and 9; the fourth be- 

 tween 9 and 7 ; rarely a fifth between 7 and the apex. In those 

 species with but three costal streaks, the one between 9 and 7 is 

 absent, and vein 9 reaches the costa nearer the apex, permitting the 

 third costal streak to be shifted backward. 



Of the dorsal streaks those at the tornus and beyond it are the 

 most constant in position. Those along the dorsal margin have no 

 defined position. 



The species may be separated as follows : 



A. Ground color of the forewings pure white, marked with fuscous irrorated 



bands and bars bataviella. 



A A. Ground color of the forewings not entirely pure white. 

 B. Forewings dusted with fuscous scales. 



C. Costal and dorsal streaks large, conspicuous and curved backward. 

 D. Size large (9-10.5 mm.) ; ground color reddish. . treiliuloidiclla. 

 DD. Size moderate (7-8 mm.) ; ground color not reddish. 



salicifoliella. 

 CC. Costal and dorsal streaks narrow, straight, forming angulated fascise. 



celtifoliella. 

 BB. Forewings not dusted. 



C. With an apical dot (indistinct in arlutnsella, insignis and obsoleta). 

 D. Without a complete median fascia. 



E. One white dorsal streak before the tornus. 



F. Two white costal streaks trinotella. 



FF. Three white eostal streaks quercialbella. 



