Dr. Karl Krapelin on the Pulicldae. 47 



there is nothing, absolutely nothing, that could lead us to 

 conclude that the Fleas were formerly in possession of any 

 such organs. Even tlie marked tripartite condition of the 

 thorax ought a priori to have banished the idea of rudi- 

 mentary wings ; nevertheless the older authors (Kirby, Dug^s, 

 &c.) have fallen into the serious error of regarding separated 

 lateral margins of the thoracic segments as such. But these 

 *' processes of the pleura3," as Taschenberg * among others 

 has conclusively proved, have nothing at all to do with wing- 

 rudiments, and are to be regarded as characteristic structures 

 sui generis. When Taschenberg therefore for this reason 

 declares the generally-employed denomination of '' Aphani- 

 ptera," founded upon this erroneous conception, to be inad- 

 missible, we can only agree with him. It is only by giving 

 up this name that we can seriously hope that the deeply 

 rooted notion of the " Diptbres sans ailes," as Strauss-Durck- 

 heim called the Fleas, will be completely suppressed. 



The wide gap which exists precisely in the most important 

 characters between the Pulicida3 and the Diptera must have 

 been made sufficiently evident by the preceding remarks. 

 That it is also expressed in other systems of organs than those 

 hitherto considered may therefore only be briefly indicated. 

 The sucking- stomach, which apparently is met with in all 

 groups of Diptera, is entirely wanting in the Pulicidfe j 

 while, on the other hand, the proventriculus beset with nume- 

 rous chitinous spines of the latter has no analogy among the 

 Diptera. The sucking-mechanism of the pharynx or of the 

 so-called " fulcrum " of the Diptera is formed by a single 

 powerful pair of muscles 5 in the Fleas, on the contrary (as 

 in the Rhynchota), a whole series of separate pairs of muscles 

 (which, however, are interpreted by Landois as flexors and 

 retractors of the labrum) are present for this function. Lastly, 

 the presence of a stigma in the prothorax of the Fleas indi- 

 cates more profound differences in the tracheal system 5 while 

 as regards the simple ocelli of the Pulicidai and the deep 

 lateral pits of the head, we may find analogous phenomena 

 among the Rhynchota, but not among the Diptera. 



After all this the Fleas cannot well remain in the order 

 Diptera. There remains then the investigation of the ques- 

 tion whether they show near relations to any of the other 

 groups of insects. Hymenoptera and Orthoptera, of which 

 earlier authors have thought in this connexion, cannot well 

 come into the question in the present state of our knowledge, 

 as it would be opposed to all rational system to assert a reia- 



* Loc. cit, p. 21. 



