172 PAPERS BY DR. B. CLEMENS. 



slender gallery or line, either simple, or enlarged towards the 

 end into a blotch, or a complete blotch. 



When the larva is full fed, it quits the mine, cutting for 

 this purpose the separated cuticle, in order to weave a minute 

 cocoon. 



The larvas of some Dipterous insects make mines that 

 strongly resemble those of some of the Nepticula, but they 

 may usually be distinguished by the more maggot-like ap- 

 pearance of the former. 



1. N. corylifoliella. The larva makes a long, winding, 

 narrow tract in the leaves of hazel in the latter part of July 

 and the beginning of August, and the fall brood may be found 

 early in October. The frass or excrement of the larva is 

 deposited along the middle of the tract, forming a minute 

 central black line. The edges of the mine are smooth, and 

 but little broader throughout its extent than the width of the 

 miner. 



The mine is left transparent by the larva from the begin- 

 ning to the end. 



There is another miner in this leaf that I suspect to be a 

 Dipteron. It makes a rather broad, tortuous tract, much 

 broader than the preceding, and the " frass " is scattered in 

 separated grains along the middle of the tract. 



2. N. ostrycefoliella. The larva in July and August 

 makes a rather wide, most frequently much contorted, trans- 

 parent mine, with a narroiv, central, black line of "frass ;" 

 sometimes the early portion of the mine is filled up with "frass," 

 and in others the line of frass is distinct from the beginning. 

 From the middle to the end of the mine whence the larva 

 escapes it will average nearly a line in width. 



3. N. Virginiella. In the leaf of iron-wood, Ostrya ; 

 makes a very narrow, long tract, not broader than the width 

 of the larva, the interior of which is filled up with dispersed 

 grains of frass, and which is dark brown whilst the larva is 



