444 DIPTERA CHAP. 



many identified as mandibles, while another pair of pointed pro- 

 cesses (c c) are considered to be parts of a maxilla, and the palpi 

 (//) ^i-s by some considered to be maxillary palps. The Danish 

 entomologist, Meinert, has published the best anatomical descrip- 

 tion of many of the diverse kinds of Dipterous mouth.-' He, 

 however, takes a different view of the morphology ; he considers 

 that not only may parts of the appendages of the mouth be much 

 modified during the early stages of the individual development, 

 but that they may be differently combined, even parts of the 

 appendages of two segments Ijeing brought together in intimate 

 combination. He has also pointed out that the mandibulate and 

 sucking mouth are mechanical implements constructed on opposed 

 principles ; the main object of a biting mouth being the fixing 

 and perfecting of the articulations of the mouth, so that great 

 power of holding may be attained with a limited but definite 

 power of movement. In the sucking mouth the parts are in- 

 timately associated for simple protrusion. Hence the two kinds 

 of mouth must have been distinguished very early in the 

 phylogeny, so that we must not expect to find a great corre- 

 spondence between the parts of biting and sucking mouths. 

 He apparently also considers that not only the appendages of 

 a head-segment, but also part of the body of the segment, may 

 be used in the construction of the mouth-organs. Meinert's 

 views allow a much greater latitude of interpretation of the parts 

 of the Dipterous mouth ; had he contented himself with enun- 

 ciating thena in the manner we have followed him in summarily 

 describing, they would have been recognised as a formidable 

 obstacle to the facile adoption of the ordinary views. He has, 

 however, accompanied his general statement with a particular 

 interpretation and a distinct nomenclature, neither of which is it 

 possible to adopt at present, as they have no more justification 

 than the ordinary view. So that instead of one set of doubtful 

 interpretations we have two.^ In so difficult a question as homo- 

 logising the trophi of different Orders of Insects we ought to use 



^ Fluerncs Munddde, Copenhagen, 1881, 91 pp. 6 plates ; Ent. Tidskr. i. 1879, 

 p. 150 ; Becher having given {Denk. Ak. Wien. xlv. 1882, p. 123) an interpreta- 

 tion different from tliat of Meinert, this author set forth his general views in 

 Zool. Anz. V. 1882, pp. 670 and 599. 



2 The reader should not suppose that there are only two views as to the Dipterous 

 mouth, for actually there are several ; our object is here only to give a general idea 

 of the subject. 



