. Elementary text-book of zoology. Zoology. 580 INSECTA. oesophagus. The maxillary palps are as a rule rudimentary (except in the Tineidce). When at rest the proboscis lies rolled up beneath the mouth, and on either side of it are placed the large three-jointed labial palps, which are often tufted with hairs and are situated on the rudimentary triangular lower lip. The three thoracic rings are intimately fused with one another, and like almost all external parts of the body are thickly covered with hairs. The wings are in most cases very large, but in rare cases are quite rudimentary (female G
. Elementary text-book of zoology. Zoology. 580 INSECTA. oesophagus. The maxillary palps are as a rule rudimentary (except in the Tineidce). When at rest the proboscis lies rolled up beneath the mouth, and on either side of it are placed the large three-jointed labial palps, which are often tufted with hairs and are situated on the rudimentary triangular lower lip. The three thoracic rings are intimately fused with one another, and like almost all external parts of the body are thickly covered with hairs. The wings are in most cases very large, but in rare cases are quite rudimentary (female Geometridce); the anterior are the largest, and are distinguished by their partial or complete covering of scale-like hairs which over-lap one another in a tectiform manner, and cause the extremely various colouring, tracing, and iridescence of the wings. These scales consist of small, usually finely ribbed and toothed plates, which are attached by styli- form roots in pores of the integument of the wings, and are com- parable to flattened out hairs. They arise during the pupal period. The arrange- ment of the nervures is of systematic value. The essential arrange- ment is a large median cell near the root of from which to eight radial ures pass to the external lateral edges, while above and below the middle cell single independent nervures run parallel to the upper or lower fringed margin. The two pairs of wings are frequently connected with one another by retinacula, the upper edge of the hind wings being covered by spines or setae, which catch in a band of the anterior wings. The legs are delicate and weak, their tibia- are armed with spurs of considerable size. The tarsuses are in general five-jointed. The abdomen has six or seven segments and is thickly covered with hairs, and ends not unfrequently with a strongly projecting tuft of hairs. Nervous system.—The brain is bi-lobed, and is provided with large. a FIG. 481.—Mouth-parts of butterflies, (after Savigny); <i, o
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectzoology, bookyear1884
