94 



ANATOMY OF AN ARTHROPOD. 



afresh to the body through' the opening in front by a rhythmical 

 contraction of the walls of the tube. There are no blood-vessels 

 as in higher animals ; the blood is poured into the body cavity, 

 and there bathes the organs and comes in contact with the re- 

 spiratory tubes. An opaque- white 



*5 J^' ' mass of fat, the fat-hody, surrounds, 



5^ ifc^EJiL" *"' '^^ nearly so, the abdomen. 



J ..Im-^m^^ '■''"'■'' The digestive organs can be easUy 



irallt'ircll " '^ unravelled, so that each part is dis- 



v« -■■ i^PffrTf-i^- ■■'"•>' tinctly visible. The alimentary tube 



n^^^Einij is short, and convoluted in the hinder 



-BK^ffll1^« parts. The first portion is lodged in 



W^M^KJII^- <='»?. the head, and is called the buccal 



w^BxHUf " ' ' cavity, into which open two glands, 



TlgBlHfl '" '^ one on each side, the salivary glands 



^iL-^^SJ\- -1 ■ {'^ff)> ^y ^ single salivary duct in a 



^^^1^* 4^S\} median aperture. Then follows a 



_ 1% .j^By. narrow gullet or oesophagus (Oes), 



^^^^^B/ which gives rise to a thin-walled sac 



/(c. ^^^^^ which is situated in the thorax and 



—^ \^^ part of the abdomen, the crop (P). 



Fio. 34.— DiQESTivE Croaks of The crop is thin - Walled ; but the 



THK CooxBOAOH. gucceediug division, the gizzard (G) 



Oes, CEsophagus ; Sd, salivary i. i i i i n 



duct ; Sg, salivary glands ; p, Or stomach, has hard muscular 



proven triculus ; (?, gizzard; i?, ■,■, ^ . . . , , ,t 



hepatic oseca ; Mc, Maipighian walls and. contains SIX large teeth. 



tubes ; Xa, large intestine : Si, rpi t j. i. i 



mesenteron; B, rectum; M, anal J-hese alimentary parts are Known 

 tub'- isoph^Ta? glnfironT ' ».?', »« the stomatodmum, being formed 

 ga'ng?:;"''''''' ""■ ' *° ^"■^ "' by an anterior invagination in the 



embryo. The stomatodseum has a 

 chitinous liuing continuous with the cliitinous cuticle of the 

 head. Following the gizzard will be observed a short thin 

 tube, which forms a connection between the original anterior 

 and posterior invaginations of the embryo. It is called the 

 mesenteron {Si). The hinder parts of the canal are composed 

 of the small and large intestines and rectum. The proximal 



