. Diptera Nematocera (excluding Chironomidæ and Culicidæ). Diptera. ;. 149 the subject of study by more than one author. The usual sexual distinction in the comparative width of the frous, which obtains in a great many families of Diptera, does not hold good in the The head is usually diehoptic in both sexes, but occasionally it is holoptic in one or both sexes. The eyes "are usually bisected by an unfacetted cross-band or line separating each eye into t\\o fields, an upper and a lower one; the upper composed of larger and less pigmented otnmatidia (large
. Diptera Nematocera (excluding Chironomidæ and Culicidæ). Diptera. ;. 149 the subject of study by more than one author. The usual sexual distinction in the comparative width of the frous, which obtains in a great many families of Diptera, does not hold good in the The head is usually diehoptic in both sexes, but occasionally it is holoptic in one or both sexes. The eyes "are usually bisected by an unfacetted cross-band or line separating each eye into t\\o fields, an upper and a lower one; the upper composed of larger and less pigmented otnmatidia (large and brown facets); the lower composed of smaller and more strongly pigmented ommatidia (small black facets). In a few species the eyes are bisected only in one sex. Three rather large ocelli are ])resent" (Kellogg). The upper eye faces dorsally and IS composed of large facets, the lower one faces ventrally, anteriorly and laterally, and is composed of much smaller facets. Radical structural differences exist in addition between the upper and lower eye.*. Fig. 13.—Mouth-parts of a Blepharoeerid, Bihiocejyhala doanei, Kellogg (after Kellogg). The mouth-parts are complex, elongated, " the female having in addition to labium and maxillae, slender flattened elongate, saw- like mandibles; the males are without these mandibles. Both sexes have a slender elongate labrum-epipharynx, a similar slender elongate hypopharynx, a pair of slender blade-like maxillis, with 5-segmented palpi, and labium with slender elongate basal sclerite, and a pair of free fleshy terminal lobes without pseudotrachese and with palpi" (Kellogg). * For studies on eyes of divided character in other groups of animals reference can be made to " The divided eyes of Arthropods " by Kellogg Zool' Anzeig. (1898). Zimmer (Zeits. f. wiss. Zool. Isiii, pp. 236-262, 1898) on the eyes of Epiiemerid^ may also be Please note that these images are extracted from scanned page imag
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectdiptera, bookyear1912
