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their mouth, but the alimentary canal is divided into distinct 

 portions, such as pharynx, oesophagus, proventiculis, gizzard, 

 intestine and anus. The blood vessels are two in number 

 and united in heart-like sacs, but it is not true blood that 

 flows through these vessels, though it is a corpusculated fluid. 

 The nervous system consists of a set of two ganglia above the 

 oesophagus and two below. There are two pairs of testes. 



1.179. Hirudince or leeches have a double chain of gan- 

 glia united by longitudnal cords and forming a collar round 

 the gullet. The mouth of a leech is triradiate /. <?,, having 

 three jaws. In some species the jaws are provided with 

 teeth. There are two suckers, one at the anterior end and the 

 other at the posterior end. The stomach is provided with 

 lateral sacs. There are 9 pair of testes, one vas deferens and 

 a protrusible penis. The female organ is inconspicuous, but 

 the females have 2 distinct ovaries and an oviduct. 



1. 1 80. Arthropoda including the lobster class, spider 

 class, centipede class and insect class of animals, have a defi- 

 nite series of rings, the integument being hard and often 

 chitinous ; each arthromere or ring has its tergum and ster- 

 num sides. The rings dispose themselves into two distinct 

 sections, the head and the thorax going to form one section, 

 called the Cephalothorax and the abdomen another section. 

 The appendages are hilateral. The blood is true blood, but 

 there are no red corpuscles. The heart is situated longitudi- 

 nally on the back. There is a double chain of ganglia at the 

 ventral side, the foremost pair of ganglia being above the 

 gullet and they may be assumed to correspond with the brain 

 of higher animals. Metamorphosis takes place by ecdysis or 

 moulting. 



1.1 81. Crustacea. This class of arthropoda have more 

 than 8 feet some of which are abdominal. The respiration is 

 aquatic either by means of gills or by the whole surface of 

 the body. There are twenty pairs of antennae. 



1.182. Arachnid a are characterised by having 8 feet. The- 

 HHHH 



