128 THE INTEGUMENTAL SKELETON OF THE IMAGO. 



hoeck, Reaumur, and the Abbe Roffredi exercised great 

 patience in the investigation of these organs ; but it was only 

 after the genius of Savigny showed the nature of the morpho- 

 logical problems involved, and made the principle clear that the 

 mouth organs of all Arthropods possess a common underlying 

 type, that the Dipterous mouth became a puzzle, affording 

 exceptional scope for speculation to those who regard Mor- 

 phology as a field for the exercise of their ingenuity. 



Savigny, after giving a careful exposition of the structure of 

 the mouth in the Lepidoptera, says, ' I believe I may assert 

 that the mouth of the Diptera is formed of the same parts 

 as that of the Hymenoptera ' [36, p. u], and having de- 

 scribed the mouth of the Hymenoptera in general terms, but 

 without detail, he adds, ' The same organs are found separately 

 or united in the mouths of the Diptera. The lower lip exists 

 in nearly all ; it forms the proboscis properly so-called. The 

 maxillae also almost always exist ; they are the parts which 

 support the palpi, so that the Diptera have maxillary, but no 

 labial palps. When the maxillae disappear, as in the true flies, 

 it is because they are united with the lower lip. The mandibles 

 are only present in some genera. They are, for example, very 

 distinct in the Tabanidae, where they form two very fine 



65. MEINERT, ' Sur la Conformation de la Tete et sur 1' Interpretation des 



Organes buccaux chez les Insectes.' Entom. Tidskrift, vol. i., pp. 147, 

 150, 1880. 



66. MEINERT, ' Sur la Construction des Organes buccaux chez les 



Dipteres.' Ibid., pp. 150-153. 



67. MEINERT, ' Fluernes Munddele (Trophi Dipterorum).' Kjobenhavn, 

 8vo, 1881, with 6 plates. 



68. DlMMOCK, GEORGE, 'The Anatomy of the Mouth Parts and of the 

 Sucking Apparatus of some Diptera.' Small 8vo, Boston, 1881, 

 with 4 plates. 



69. BECKER, E., ' Zur Kenntniss der Mundtheile der Dipteren.' Denksch. 

 Wien. Acad., Math. Nat. Kl., Bd. xlv., 1882. Gives the literature of 

 the subject very fully. 



70. KRAEPELIN, K., 'Zur Anatomic und Physiologie des Riissels von 



Musca.' Zeitsch. f. w. Zool., Bd. 39, 1883. 



71. LOWNE, B. T., ' On the Head of the Blow-fly Larva and its relation to 

 that of the Perfect Insect.' Journ. Ouekett Micr. Club, ser. ii., vol. iii., 

 p. 120, 1887. 



