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MANUAL OF ZOOLOGY. 



with antennsE, jaws, and usually simple eyes. The mouth of 

 the caterpillar, unlike that of the perfect insect, is formed for 

 mastication. The labium also is provided with a tubular organ 

 — the " spinneret" — which communicates with two internal 

 glands, the functions of which are to furnish the silk, whereby 

 the animal constructs its ordinary abode or spins its cocoon. 

 The three segments behind the head correspond with the pro- 

 thorax, meso-thorax, and meta-thorax of the perfect insect, and 

 each carries a pair of jointed walking-legs. Besides these 

 thoracic legs, there is a variable number, (generally ten) of soft 

 fleshy legs, which are borne by the segments of the abdomen, 

 and are known as "pro-legs." Each is usually furnished with 

 a crown of small horny hooks, and they are never attached to 

 the 4th, sth, loth, and nth abdominal segments. 



Fig. 93. — Large White Cabbage Butterfly {Pontta hrassica). a Larva or caterpillar; 

 b Pupa or chrysalis ; c Imago or perfect insect. ^ 



In the Diurnal Lepidoptera, or Butterflies proper (fig. 93), 

 the antennae are knobbed; the wings are usually held erect 

 when the insect is in a state of repose; the larvse have six 

 thoracic legs, and ten pro-legs ; and the pupse are always 

 naked, attached by the posterior extremity or head downwards, 

 and usually angular. 



In the Crepuscular Lepidoptera, including those forms which 

 are active during the twilight, the antennae are fusiform, or 

 grow gradually thicker from the base to the apex ; the wings 

 are horizontal or Uttle inclined wl^en the insect is at rest ; the 

 posterior wings have their front margins furnished with a rigid 



