PHYLOGEXY OF THE XEMOCERA. 263 



are small, and have functional ocelli and pulvilli. The mouth- 

 parts are much less specialized (the mentum being developed) 

 and they retain some remarkable archaic characters. I would 

 protest against the time-honored custom of subjecting all other 

 characters of Diptera to the venation. 1 



This reconstruction of the primitive dipteron by Williston 

 has given me much pleasure and much food for thought, though 

 I am not in agreement with him in his views of the labial palpi. 

 I think that the primitive dipteron had, like all other contem- 

 porary insects, four palpi, and that they persisted in this con- 

 dition until after the chief phyla had arisen, since a large majority 

 of the Empidse have what I believe to be undoubted labial 

 palpi. I have no doubt that the structure of the labium in 

 Chrysops, which I figured in 1904 in the cited paper on mouth- 

 parts, shows aborted labial palpi, the palpigers. Savigny, in the 

 dawn of orismology, pointed out remains on the labium of 

 Tabanus italicns, and I can show a number of preparations in 

 the same family with tufts of hair in similar situations to the 

 palpigers of Chrysops. 



Loss OF ANTENNAL JOINTS. 



Williston discusses this subject on pages 328, 329 of the cited 

 paper; some observations by myself may throw additional 

 light upon it. I have in my cabinet a preparation of Scatopse 

 of very small size, probably 6 1 . minutissima Verrall., in which 

 the antennae are unsymmetrical. The fourth and fifth joints 

 are partially fused in the left antenna, the suture going only 

 half through the segment; the right antenna has the full number 

 nine of antennal joints, with the fourth and fifth separated 

 (Figs. 1,2); here we can clearly see that a middle joint has been 

 lost. In preparations of Diloplnts and Bibio, where, judging 

 from the variations in number in different species, the antennas 

 are in an unstable condition I have several specimens where 

 the distal joint consists of from three to six segments closely 



1 I will not quarrel with this conclusion, though I still think that holopticism 

 outweighs in importance the archaic characters of ocelli and pulvilli and even of 

 the mouth parts. It is quite evident, however, that the Rhyphidae should no 

 longer be placed at the extreme end of the Nemocera. S. W. WILLISTON. 



