10 BEACHYCEEA. 



The external characters of the BEACHYCEEA and CYCLOEEHAPHA 

 exhibit as much, it' not greater variation than those of the 

 NEMATOCEEA. As the introduction to the previous volume on 

 Diptera dealt with characters common to 4he order generally, 

 those pages may be consulted in conjunction with the present 

 summary, which is confined to the BEACHYCEEA and those families 

 of the CYCLOEEHAPHA treated of herein. 



The eyes in the higher BEACJIYCEEA and higher CYCLOBEHAPHA 

 are generally contiguous or subcontiguous above in the male, and 

 such flies are said to be holoptic, the eyes in the female being 

 distinctly separated hy a comparatively broad Irons, but exceptions 

 are numerous. Diptera in which the eyes are well separated in 

 the c? are called dichoptic. The CYETID/E have contiguous eyes 

 in both sexes (with rare exceptions), and in some cases the eyes 

 are contiguous both above and below ; the MYDATD^, ASILLIXI;, 

 DOUCHOPODIM:, LONCHOPTEEIDA-, and COXOPIDJE have the eyes 

 equally conspicuously separated in both sexes. The lower ANTHO- 

 MYJNJE and practically all the ACALYPTEATA are also dichoptic. 

 The eyes may be pubescent or bare, this being sometimes a sexual 

 character, and iu life they are often green (Hcematopotci) or golden 

 green (Chrysopihts), and in many species of TABANIDJE, ASILID^E 

 and some other groups bear brown or purple bands. In many 

 groups the front facets are from just perceptibly to very con- 

 siderably larger than the rest in the c? , and of uniform and 

 smaller size in the 5 , but in the PIPUNCULID.E the front facets, 

 though enlarged more than usual in the d , are yet more enlarged, 

 and to an enormous extent, in the 5 . In some PUPIPAEA the eyes 

 are absent ; in CYETID.E and PIPUNCULID.E they occupy practically 

 all the head, no other parts except the antenna? being visible in 

 profile in some species of both families. 



Three ocelli are normally present in all the BEACHYCEEA, but 

 they are occasionally absent (CONOPIN^E). 



The lower part of the head, or epistome, exhibits a wide range 

 of shape and size, from being barely or not at all produced beyond 

 the eyes in profile either forwards or downwards (as in most 

 PIPUNCULIDJE) to forming a long strong conical rostrum (Nemotehts 

 in STEATIOMYIDJE ; Khingia, Volucella, Lycastris in SYEPHIDJE). 

 The face frequently has a central bump, as in most SrEpHiD^E, or 

 it may be less prominent, gently curved, or flattened. The mouth- 

 parts attain their highest development in the TABANID.E, a family 

 in which the females of all the species have the reputation of 

 being blood-suckers. The parts of the female Tabanid mouth 

 consist of the labiuin or lower lip, a pair of maxilla? and of 

 mandibles, strong piercing organs, and a pair of large, fleshy, 

 conspicuous, approximately conical maxillary palpi.* The pro- 

 boscis in the BEACHYCEEA is usually soft, and formed for sucking 

 the juices of plants or animal matter, but it is not infrequently 

 of enormous length, longer than the whole body and of extreme 



* Compare ' Indian Diptera,' i. p. 18. 



