﻿MOUTII-PAKTS 



44 3 



subject to great diversity of structure within the limits of the 

 Order itself, even the two sexes in some- species differing pro- 

 foundly in this respect. 1 In the majority of the family Oestridae 

 the mouth-parts are practically absent, and no definite entry to 

 the alimentary canal can be perceived (Fig. 245). Besides this 

 condition and its antithesis (Fig. 214;, the complex assemblage 

 of lancets seen in the Breeze-flies that draw blood, there is a 

 great variety of other anatomical conditions. 



Fig. 214. — Mouth - parts of 

 the common blood-suck- 

 ing fly, Haematopota 

 pluvialis y. A, Viewed 

 from beneath, the pro- 

 boscis removed : a, 

 labrum ; 6, b, cultelli 

 (mandibles of other 

 anatomists) : e, c, scal- 

 pella (maxillae of other 

 anatomists i ; d, part of 

 ventral scutum of second 

 metamere ; e, e,f,f, parts 

 of palpi ; .'/- hypopharynx 

 and pellucid salivary 

 duct ; h, salivary recep- 

 tacle : i, salivary duct ; 

 /.. membranous part of 

 second metamere : I, 

 pharynx : B. labrum. 

 pharynx, hypophary n x . 

 separated, seen from 

 beneath ; a, labrum ; b, 

 C. proboscis 



A 

 hypopharynx ; 



salivan 



, d, pharynx ; e, protractor muscles . 

 (labium) from beneath ; a, scutum proboscidis ; c, c, labella : d, d, retractcr muscles. 

 (After Meinert). 



Although, as we have said, great diversity of opinion 

 exists, yet on the whole the majority of Dipterologists accept a 

 view something to the following effect : — the labrum, or the 

 labrum combined with the epipharynx, is frequently much pro- 

 longed ; the tongue — hypopharynx — may also be much prolonged, 

 and may form, in apposition with the labrum, a more or less im- 

 perfect tube for ingestion of the nutriment; the labium is more 

 or less membranous or fleshy, and acts as a sheathing organ, its 

 tips — called labella — being in some cases developed to a quite 

 extraordinary extent. As to the other parts of the mouth there 

 is less agreement; the pointed organs (Fig. 214, A, b b] are by 



1 It is frequently said that one sex of a single species may be dimorphic in this 

 respect, bui we shall subsequently mention in Blepharoceridae) that this is not 

 yet sufficiently established. 



