REPORT OF THE STATE ENTOMOLOGIST I907 24I 



Limnobiinae. In this subfamily my material has been more 

 abundant. The tribes appear to be founded too often on the pres- 

 ence or absence of parts; and usually it is not the presence or 

 absence of a part that is most significant, but the form it assumes 

 when it is present. Some such characters, however, as spurs and 

 empodia, which Osten Sacken conceived to be rudiments, of no con- 

 sequence to their possessors he used with great confidence.^ Ordi- 

 narily, these doubtless served him well, but I think they have led 

 to a few incongruous associations of genera. The use of antennal 

 characters hitherto has consisted mainly in the counting of their 

 segments and is very superficial. Of venational characters, he dis- 

 covered that the branching of the radial sector is much more con- 

 stant than that of media, but clearly the number of branches of the 

 sector and the amount of retraction of Sc^ — the characters of 

 which he made most use — are characters of degree only, and like 

 the waning spurs, and imperfect segmentation of antennae, are 

 liable to prove unreliable at critical points. His grouping in sections 

 are in the main natural assemblages, for he based them on keen 

 scrutiny of all the -characters he could discover. He was certainly 

 wrong, how^ever, in considering the Limnobiini a group of archaic 

 forms [loc. cit. p. 75], for the reduction of branches of the radial 

 sector, of segments in the antennae, and of spurs and empodia, are 

 all departures from primitive conditions. 



The Cylindrotomini are distinguished from the other tribes or 

 sections by a pronounced tendency of R^, R^ and R^ to fuse together 

 in one long straight vein tip. Rs is always two branched ; Sc^ never 

 tends to recede toward the wing base independently, but the entire 

 tip of Sc often atrophies. Media at its first fork is strongly skewed 

 forward, so that Cu^ is in line with the median stalk, and when 

 veins M^ and M^ are both present and separate, M^ tends to be 

 strongly deflected upward at its base (a condition noticed elsewhere 

 only in Penthoptera. 



The Limnophilini are a generalized group of Limnobiinae, and 

 generally lack the special features of the other sections. Rs is three 

 branched and typical for this subfamily. Sc is usually forked at 

 its tip, except in the aberrant Podoneura and Trichocera. Media 

 is three branched except in Ulomorpha and Phyllolabis [pi. 

 26, fig. 5] and a few species of Limnophila, and its first 



1 See Osten Sacken. On the atavic index characters, with some remarks 

 about the classification of the Diptera, Bed, ent. Z^\\. 1894. 39:69-76, 



