. The Cambridge natural history. Zoology. MOUTH-PARTS 443 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.^ 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. FlQ. 214.—Mouth-parts of the common blood-su
. The Cambridge natural history. Zoology. MOUTH-PARTS 443 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.^ 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. FlQ. 214.—Mouth-parts of the common blood-suck- ing liy, Haemat023ota plm-ialis ?. A, Viewed from beneath, the pro- boscis removed ; a, labrum ; b, b, cultelli (mandibles of other anatomists) ; c, c, scal- pella (maxillae of other anatomists) ; d, part of ventral scutum of second metamere ; e, e,f,f, parts of palpi ; g, hypopharynx and pellucid salivary dnct; /i, salivary recep- tacle ; i, salivary duct; k, membranous part of second metamere ; i, pharynx : B, labrum, pharynx, hypopharynx, separated, seen from beneath ; a, labrum ; 6, protractor muscles: C, proboscis e, labella ; d, d, retractor A hypopharynx ; t, salivary dnct; d, pharynx ; ^(labium) from beneath ; a, scutum proboscidis ; (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 h) are by ' It is frequently said tha
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectzoology, bookyear1895
