4U 



PSrCHE. 



[November — December iSgo. 



homology. It is utterly unphilospho- 

 cal to accept without the clearest proof 

 such a structural modification as this 

 change in position of the mandibles 

 would require, and the modification of 

 the ordinary labium into a beak of this 

 character is a process that ought to be 

 proven. It seems to be assumed that the 

 "labium" of the hemiptera is the same 

 as the "labium" of the diptera, e. g. 

 Ciilex^ and if this is so, I have a paper 

 now in press, in which I claim to prove 

 that this "•labium" in the diptera is 

 really only a modified galea, or a max- 

 illary structure. I hope to prove some 

 time in the future, when I can get the 

 necessary material, how this modifica- 

 tion of the hemipterous mouth came 

 about, and that the mandibles do not, 

 habitually, become internal mouth 

 structures so long as there are other 

 organs enough more naturally situated. 



Explanation to base figures. 



Fig. I. Siphonophora avenae. a, beak; 

 b, bristles of mouth — '•mandibles" and "max- 

 illae;" c, antenna of winged vis'iparous 

 female. 



Fig. 2. Aphis brassicae. a, antenna of 

 wingless forms ; b, antenna of winged vivi- 

 parous female; c, beak of young lice; d, beak 

 of mature, winged tbrm. 



¥n 



Aphis cuciitneris. a, antenna of 



winged viviparous female ; b, beak of wing- 

 less forms. 



Fig. 4. Myzus cerasi. a, 3rd ; b. 5th ; 

 c, 6th joint of antenna of winged viviparous 

 female. 



Fig. 5. Aphis persicae-niger. a, antenna 

 of immature forms, joints 5 and 6; ^, 3rd; 

 c, 4th; d, 5th; e, 6th joint of antenna of 

 winged viviparous female; f., sensory pit 

 from front; g^ same from side. 



NOTES ON TWO SPECIES OF DATANA WITH DESCRIPTIONS OF 

 THEIR LARVAL STAGES. 



BV HARRISON G. DYAR, HHTNEBECK, N. Y. 



Of all the closely related species of 

 this genus, the two which approach 

 each other the most nearly and are most 

 diflficult to distinguish in the imago 

 state, are D. major and D. drexelil. 

 I have elsewhere called attention to the 

 main feature by which they are to be 

 distinguished, which, after all, is only 

 a matter of degree of coloration. The 



species dift'er, or rather tend to differ, 

 in other points beside the brightness of 

 the costal shade, namely, in the more 

 entire outer margin of the primaries, 

 and the darker more even coloration of 

 the wings of D. 7na.jor. 



The size is the same in both species, 

 there are no markedly distinctive male 

 gfenital characters, and the lines and 



