860 Charles Paul Alexander 



are of great importance in classification. These spurs are lacking in the 

 tribes Limnobimi, Antochini, and Eriopterini, but are present in the 

 remainder of the Tipulidae tho in some cases they are so small as to 

 require a low-powered microscope for their detection. 



The tarsal segments. — The tarsus, or foot of the fly, is made up of the 

 terminal five segments. The first of these segments is the longest and 

 is called the metatarsus. The remaining segments gradually decrease 

 in length to the last, which bears the claws, or ungues, and, when it is 

 present, the emyodium between the claws. In Bittacomorpha the 

 metatarsus is swollen and bladder-like. In one species of Lecteria the 

 metatarsus bears a group of three stout spines at the extreme base. 

 The claws of most crane-flies are quite smooth (fig. 127, c, Rhabdo- 

 mastix), but those of species of the tribe Limnobiini have teeth on the 

 ventral side (fig. 127, A, Limnobia; fig. 127, b, Dicranomyia) . A sim- 

 ilar condition is found in certain Dolichopezini, such as Brachypremna 

 and Tanyprenma, but not in Megistocera. 



The transverse suture 



The transverse suture is considered one of the important characters 

 for use in distinguishing the Tipulidae from related families of flies, such 

 as the Dixidae, the Mycetophilidae, and others. It is in the shape of 

 a low V, and separates the mesonotal prescutum from the scutum. 



The wings and their venation 



The wings of crane-flies, with their remarkably constant venation and 

 pattern, furnish the easiest and best characters for recognition of the 

 various forms. In the great majority of cases a glance at the wing is 

 sufficient for the determination of the species, and it is for this reason 

 that considerable emphasis is here placed on these organs. This paper 

 discusses only in a rather elementary way the essentials of the wing 

 venation, but Needham (1908) has made a critical survey of the character 

 in all the genera of the Tipulidae known at the time his work was pre- 

 pared, and his paper is absolutely essential to the student of this group 

 of insects. 



The wing is made up of a series of longitudinal veins running 

 from the base to the outer margin and bound together at various points 

 by cross-veins and by deflections of the longitudinal veins which produce 



