434 Osten Sacken: on the characters qf the three divisions of 



thc water (FÄliptei^a, Aniocha) have glabrous eyes; the same is tl'.e 

 case with Shmdiwn among the Nem.. anomala. 



Thc majority of the Nemocera vera have no ocelli; tliese occnr 

 only \\\ the Mycetophilidae, and in the smaller of the two groups of 

 the Cecidomyidae, the Lestremina, which seems to bc related to 

 the Mycetophilidae. They also occur exceptionally in a Single genus 

 of the Tipididae, TrichoceraJ) 



As if in compensation for their sniall heads and eyes, the true 

 Nemocera show a large developnient of the antennae. It is in this 

 organ, and not in the eyes, as in many other Diptera, that the ce- 

 phalic secondary sexual character of the faniily finds its expression. 

 The antennae of the male are longer, often count more joints, and 

 are more hairy than the antennae of the female. Other secondary 

 sexual characters occur in the relative length of the palpi (Cidex), 

 in the size and shape of the wings {Tipididae, Chironomidae etc.), 

 the general shape of the body etc. But such characters are not cha- 

 racteristic of the Nemocera alone, and therefore do not require a 

 particular notice here. The coriaceous pouch of the male Ulomyia 

 (Walker, Ins. Brit. Dipt. III, p. 261, Tab. 26, f. 3a) reminds one of 

 some formations on the wings in certain male Dolichopodidae. 



In some groups the sexual character connected with the antennae 

 is much more developed than in others. The Oidicidae and Chiro- 

 nomidae in most cases have bushy antennae in the male, and not in 

 the female. Ctenophora and Rhipidia have pectinate antennae in 

 the male only. In some Tipididae, like Megistocera, Macromastiv 

 and some Eriocerae the antennae of the male are enormously pro- 

 longed, while those of the female are short, Some Cecidomyiae 

 (Diplosis) have in the male twice as many joints of the flagellum as 

 the female; in other cases the antennae are petiolate in the male and 

 sessile in the female. 



The size of the antennae in the true Nemocera, especially in 

 the males, in comparison with their small heads, is worth noticing, 

 and the contrast in this respect with other families of Diptera is 

 striking. We have already mentioned above (p. 424) Bibio and Si- 

 midiiim with their large heads and small antennae. We may imagine 

 how enormous the antennae of a Tahanns would be, if they stood 

 in the same proportion to the head, as the antennae of some male 

 Cecidomyiae. 



i) Schiner (Fauna II, p. XXVIII, footnote) observes that the mi- 

 croscope reveals traces of ocelli in some of the Chironomidae, especially 

 of Tanypus. About this compare the Additions, 



