438 Osten Sacken: on the cliaraders of the three divisions of 



whole leg is stoiiter than usiial; or the hincl femora only; the tibiae 

 are sometimes flattened; the relative length of the metatarsus Is va- 

 riable; the claws are large or small; equal, or unequal; simple, or 

 bifid, or dcutate; sometimes, thcrc is a distinct empodium, or there 

 are a few hairs instead; the underside of the femora and that of the 

 metatarsi, especially of the last pair, are often beset with spines or 

 Short bristles. i) On the legs of other Chironomidae charactcristic 

 hairy fringes sometimes appear. In the Tipididae, the prescnce or 

 absence of spurs at the end of the tibiae, and the presence or absence 

 of empodia, afford excellent characters for the definition of larger 

 divisions only, not so much for genera and species. The same is the 

 case with the spines and spurs used for the characterization of the 

 groups of MycetopMUdae. The flies of the latter family are very 

 active, with comparatively streng legs, especially the bind pair, with 

 which, according to Westwood (Introd. II, p. 521) they are capable of 

 leaping. The exceptional Platyura from New-Zealand, more than 

 once mentioned in the present paper for its peculiarities, has very 

 decidedly clavate bind femora, very much attenuate at the base; an 

 unusual structure among Nemocera. Cecidomyia has a remarkablc 

 charactcr in the brevity of the first tarsal Joint; it was, I believe, 

 lirst noticed by Meigen and published in 1818. 



Tipididae and Cidicidae alight on their legs, but do not run 

 much. Small Chironomidae, Cecidomyidae, Mycetophilidae (espe- 

 cially Sciara) and Psychodidae run very well, but with a light tread, 

 not with the slow galt of a Bibio, or the plantigrade one of a Si- 

 mulium. The long legs of the large Tipidae serve them as balancers 

 during their unsteady, headlong flight, and as buffers in case of 

 contact; their prehensile tarsi as hooks for suspending themselves on 

 trees, leaves and grasses. 



Empodia occur among the true Nemocera^ but never pulvilli. 

 In some larger Chironomi (for instance Chi7\ plumosus) what I take 

 to be merely a broad and bifid empodium assumes the appearance of 

 a pair of pulvilli. — 



The empodia of the Nemocera vera have beeu very much 

 neglected by describers, and either entirely overlooked, or promis- 

 cuously called pulvilli. In Winnertz's papers on the Mycetophilidae 

 and Cecidomyidae I do not find anything about these organs. In 

 his paper on Ceratopogon Winnertz calls pulvilli, what in reality 

 are empodia. Ahout Chironomus Schiner says: „pulvilli (Haft- 



i) Compare also the Statements of Loew, Bernstein u. Berusteinfauna 

 p. 30, about the curious Ceratopogons in amber. 



