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MANUAL OF ZOOLOGY; 



usual form. The maxillae and the labium are greatly elon- 

 gated ; the former being apposed to the lengthened tongue in 

 such a manner as to form a tubular trunk, which cannot be 

 rolled up, as in the Butterflies, but is capable of efficient suc- 

 tion. The labial palpi are also greatly elongated. 



In the Hemiptera, the " trophi " consist of four lancet-shaped 

 needles, which are the modified mandibles and maxillae, en- 

 closed in a tubular sheath formed by the elongated labium 

 (fig. 84, 3). Lastly, in the Dipiera — as in the common House- 

 fly — there is an elongated labium, which is channelled on its 

 upper surfa,ce for the reception of the mandibles and maxillsB, 

 these being modified into bristles or lancets. 



The mouth in the Masticating Insects leads by a pharynx 

 and oesophagus into a membranous, usually folded, stomach 

 — the " crop," or " ingluvies " — from which the food is trans- 

 mitted to a second muscular 

 stomach, called the "gizzard" 

 (fig. 85). The gizzard is adapt- 

 ed for crushing the food, often 

 having plates or teeth of chitine 

 developed in its walls, and. is 

 succeeded by the true digestive 

 cavity, called the " chylific sto- 

 mach " {ventriculus chylopoieti- 

 cus). From this an intestine 

 of variable length proceeds, its 

 terminal portion, or rectum, 

 opening into a dilatation which 

 is common to the ducts of the 

 generative organs, and is termed 

 the "cloaca." The oesophagus 

 is furnished with salivary glands 

 of varying size and complexity, 

 and is provided in some of the 

 Suctorial Insects with a dilata- 

 tion called the " sucking sto- 

 mach." Behind the pyloric 

 aperture of the stomach, with 

 very few exceptions, are a vari- 

 able number of caecal, convo- 

 luted tubes (fig. 85, e), which 

 open into the intestine, and are 

 called the " Malpighian tubes." 

 These are often looked upon as representing the liver, but 

 are by some believed to have a renal function. If the Malpig- 



t'ig. 85. — Digestive system of a Beetle 

 [Carabus aiirafus). a (Esophagus ; li 

 Crop : c Gizzard ; d Chylific stomach ; 

 e Malpihgian tubes ; / Intestine ; g 

 Cloaca ; k Supposed renal vessels. 



