160 PROCEEDINGS ENTOMOLOGICAL SOCIETY 



power of a compound microscope. Ad-2a revolves almost com- 

 pletely around seta Ad-2 in the Gelechiidae, and Pd-2a is equally 

 migratory in many groups. I have found, however, no very strik- 

 ing differences among species of the same genus and within fam- 

 ilies even the tendencies of migration are limited in certain direc- 

 tions. It is never a serious problem to homologize these punc- 

 tures. The one I have designated as Pel-la offers the most diffi- 

 culty on account of its frequent proximity to L-l and Ad-3. That 

 it really belongs with the Posterodorsals and indicates the devel- 

 opment of that group is shown in Gnorrimoschema and Nealyda 

 where it is closely approximate to Pd-2a, lying almost midway 

 between the two primary Posterodorsal setae. 



Changes in position of setae and punctures within the setae 

 groups in any given family are most frequent with Ad-2, Ad-2a, 

 0-1, Pd-la and Pd-2a and less frequent with Ad-3, L-la, 6-2, and 

 3, and the Posterodorsal and Subocellar setae. In fact, no group 

 is so nearly uniform in the arrangement and the position of its 

 individual setae throughout the Micros as the Subocellar group. 1 



The secondary tubercles of the Posterodorsal area vary greatly 

 in number and character. In many cases they differ on the two 

 epicranial lobes of the same head and are frequently undistinguish- 

 able even under high magnification. 



. THE TROPHI. 



Among the trophi we find our best characters on the labrum 

 and the so-called maxillulae and in the arrangement of the ocelli. 

 On its upper surface the labrum bears twelve primary setae ar- 

 ranged in two symmetrically paired groups of three each (Fig. 1). 

 The outer three are always located upon the area represented on 

 the ventral side of the labrum by the epipharyngial rods (Fig. 2) . 

 The development of these rods determining the relative position 

 of the setae, the foremost seta being always at the front extrem- 

 ity. These three setae also have a common nerve connection 

 near the base of the labrum. The three medial setae also form a 

 natural group with separate nerve connections from the laterals. 

 As Forbes' (5) numbering of these setae contradicts their mor- 

 phology I am proposing the symbols M 1-2-3- for the medial 

 group and L 1-2-3- for the lateral, numbering from the base of 

 the labrum forward. The punctures are treated as subprimaries 

 of the medial group. Fig. 1 shows the homology with Forbes' 



1 Dampf's division of the setae within and below the area occupied 

 by the ocelli into two groups is a convenient one for purposes of descrip- 

 tion and identification but the name ocellar and Subocellar are somewhat 

 misleading as 0.1 often falls well below the ocelli and SO-2 as frequently 

 within the ocellar area. 



