Archive image from page 174 of The anatomy, physiology, morphology and. The anatomy, physiology, morphology and development of the blow-fly (Calliphora erythrocephala.) A study in the comparative anatomy and morphology of insects; with plates and illustrations executed directly from the drawings of the author; CUbiodiversity4765349-9885 Year: 1890 ( THE OF THE PROBOSCIS. 149 the dorsal surface is lengthened by the elongation of the meso- labrum and the palpigerous scales. The oral lobes are also pro- portionately longer than at a later period. At a still earlier period of develo
Archive image from page 174 of The anatomy, physiology, morphology and. The anatomy, physiology, morphology and development of the blow-fly (Calliphora erythrocephala.) A study in the comparative anatomy and morphology of insects; with plates and illustrations executed directly from the drawings of the author; CUbiodiversity4765349-9885 Year: 1890 ( THE OF THE PROBOSCIS. 149 the dorsal surface is lengthened by the elongation of the meso- labrum and the palpigerous scales. The oral lobes are also pro- portionately longer than at a later period. At a still earlier period of development in the nymph (Fig. 32), the labrum is less displaced in relation to the theca than in the newly-escaped imago. The head is then smaller, and it is apparently the unequal growth of the head which pushes the labrum towards the distal extremity of the proboscis. During the evolution of the proboscis, after the escape of the imago from the pupa, the ventral (upper) surface of the proboscis is gradually elongated, and the discophore is converted into a portion of the dorsal surface of the oral sucker, whilst the Fig. 32.—A longitudinal median section of the proboscis of a nymph, about the middle of the second week : a, boundary of air space between the hypodermis and the pseudotracheic of the disc ; /', aggregations of embryonic cells ; ,-,, folds of the rostrum ; d, the discophore ; / /;, the pharynx ; in I, tlie mcso- and / /, the prelabrum ; sg, labial gland ; s s, the sheath. theca assumes its position above the labrum. At the same time the cylindrical portion of the rostrum becomes shortened and conical, whilst the part is converted into a membranous cone. d. The Comparative Anatomy of the Proboscis in the Diptera. The form of the proboscis in the immature imago of the Blow-fly affords an easy transition between the most diverse types of the dipterous mouth. The various modifications of 10—2
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