INTRODUCTION. 7 



body. The fleshy processes are sometimes, especially iu the 

 Tipididse, strengthened on the inner side by small horny plates . 

 sometimes they are replaced by horny, pointed processes (I have 

 found a larva of this kind, belonging to Tipula or Pachyrrhina). 

 The larvae of some ClenojjJioree (as G. atrata, nigrico7-nis, etc., 

 belonging to the subgenus Xiphura Brulle), have no processes at 

 all round the truncature. In the aquatic larva) of Plychoptera, 

 a long tube at the end of the body, serves for breathing, for which 

 purpose it is raised to the surface of the water. 



On the under side of the last segment is the anal opening. 

 Immediately" in front of the anus, on the under side of the body, 

 some larvae, belonging probably to the genus Tipula, have a 

 certain number of soft, digitiform, retractile processes, varying in 

 size, shape, and number. (The usual shape is figured in Reaumur, 

 lY, Tab. XIV, f. 10, where there are six large processes; but 

 sometimes they are much smaller.) I do not know the use of 

 these singular organs. 



The pupae of the Tipulidse are extricate, like those of nearly 

 all the Diptera orthorapha. The thorax usually bears two horn- 

 like processes, varying in length apd structure. They repi'esent 

 the thoracic spiracles. In Plychoptera one of these processes 

 acquires a great length, in order to allow the pupa to breathe 

 under water. The abdominal segments of the pupa are provided 

 Avith transverse rows of hairs, bristles or spines, which enable 

 the pupa to extricate itself from its place of concealment, pre- 

 paratory to the escape of the perfect insect. These processes 

 are usually more numerous and stronger iu the genera Tipula, 

 Ctenophora, etc., than among the brevipalpous Tipulidae. 



3. Historical account of the classification of the Tipididae. 



The word Tipula was used by the Latin classics to designate 

 some long-legged insect, running over the surface of the water, 

 perhaps Hydrometra. I have not been able to ascertain when 

 and where this word was first applied to the crane-flies ;' but it 



' The quotations from Plautus, Varro and Festus about Tiptda or Tippulla, 

 are to be found in all Latin dictionaries. Aldrovandi, whose work, De 

 Animalibus Insectis, appeared in 1602, reproduces these quotations (p. 708), 

 and describes as Tipulre two water insects ; one of them is Ranatra, which 

 is also figured ; the other is apparently Hydrometra. Moufet (Insect. Theatr. 

 1 334), under the name of Tipula, likewise means Hijdrometra (p. 169); but iu 



