INTRODUCTION. 3 



great majority of them have 2 -f 11, 2 + 12 or 2 + 1-4 joints; 

 the great majority of the Mycetophilidse have 2 + 14, the 

 CuUcidse 2 + 12, the Chironomidse from 2 + 10 to 2 + 13 (in 

 the niale sex ; much less in the female) ; the Cecidomyidse 2 -{- 12, 

 or double this number, 2 + 24. 



The feet of the TijyuUdse are comparatively much longer than 

 those of the other families of Diptera nemocera (except perhaps 

 the Blepharoceridee) ; but the coxse are never so long as in the 

 2Iijcetophilidae, the femora never dentate, as in Cei^atopogon ; the 

 tibiae, although often spurred at the tip, are never beset with 

 spines, as in the majority of the Ilycetophilidae. The ungues 

 have sometimes teeth on the under side, like those of some 

 Chironomidse and Mycetophilidse; empodia are often distinct, 

 but pulvilli, like those of Bibio, have not been observed. 



In size, *the majority of the Tipulidse are considerably larger 

 than the other Diptera nemocera, and the contrast in this respect 

 is very striking. 



Among the families usually placed in the vicinity of the Tipu- 

 lidse, the Blepharoceridx alone may have a claim to a distant 

 relationship with them. In the structure of the incomplete 

 thoracic suture of Blepjharocera, I perceive, if I am not mistaken, 

 an approach to the Ptychopterina ; but as my knowledge of the 

 Blephai-oceridse is confined to a single species, I would not insist 

 upon this relationship. The Blej)haroceridse have three ocelli 

 and a peculiar venation ; the inner horny parts of the mouth of 

 Blepharocera are much more developed than those of the Tipu- 

 lidse ; and the eyes are divided by a distinct cross-line into two 

 portions, one with large, the other with small facets ; a character 

 which I have never observed among the Tipulidse. 



The connection between the Psychodidse and the Eriop)terina 

 is of a very obscure kind, and unless further developed by obser- 

 vation, cannot have any scientific value. 



The position of the genus Chionea among the Tipulidse, is 

 determined chiefly by the structure of its ovipositor, the want of 

 a thoracic suture notwithstanding. Moreover, the relationship 

 of Chionea to Trimicra is evident. 



The case of Dixa, likewise deprived of a thoracic suture, is 

 more doubtful. This genus has been referred to the Myceto- 

 2>hilidae by Meigen and Zetterstedt ; to the Tipulidse by 

 Macquart and Westwood j Rondani connects it with Trivhocera, 



