same thing, — eitlier as fascia in process of formation by union 

 ot opposite streaks, or as fascia breaking up into streaks — and 

 the apical dusting and spot are very variable in many species, 

 and are only different phases of the same phenomenon. 



Altogether Lithocolletis is a very well marked and homo- 

 geneous genus of beautiful and gaily colored little moths, and, 

 as a genus, is perhaps unsurpassed in beauty, though Cemios- 

 toma and individual species of other genera, as Lithariapteryx 

 ahroniaeella Cham., or Strohisia viridipenneUa Clem, (the rival 

 queens of the Tineina, in my judgment, and even the rivals of 

 any Papilio, Ornithoi)tera, Charaxes, or Urania), may surpass 

 any individual species of Lithocolletis. L. ornatella will, how- 

 ever, " hold up its head with the best." V. T. Chamhers. 



On the Structure of the Head of Atropos. 



In the last number but one of Psychj; (vol. ii, 49-51) Mr. 

 Scudder has called attention to the erroneous description, by 

 previous authors, of the mouth parts of Atropos, the common 

 book-louse. Recent dissections of these parts, made not only 

 on Ati-opos, where their minuteness renders study very diffi- 

 cult, but also on Psocus, leads me to believe that Mr. Scudder, 

 equally with his predecessors, has failed to recognize their true 

 structure. As I hope to give the results of my studies in 

 detail elsewhere,^ I will confine myself at present to the anat- 

 omy of Atropos. 



It is somewhat singular that the structure of the maxilla in 

 the Psocidae has never received more attention, as it seems to 

 have no parallel among other insects. In Atropos and other 

 members of this family, the maxilla consists of two small basal 

 joints bearing outwardly a normal four-jointed palpus, and in- 

 wardly a broad, thin blade, narrower towards the tip, which 

 curves over so as to form a sort of cover or " galea " to the 

 sides of the mouth. As the thickened rim of one blade 

 strikes on that of the opposite one (at least in Psocus), this 

 organ may be usi^d to aid the woi-k of the mandibles in biting. 



1 Proc. Bost. Soc. Nat. Hist, xix, 291. 



