ABDOMINAL APPENDAGES. 



623 



bryo Insects exhibit similar structures. Finally there are 



certain structures borne at the hinder end of the abdomen 



which are regarded by some, though there is no general 



agreement on this point, as of the nature of limbs. Amongst 



these are (i) the cercopcds 



or cerci anales, usually seg- 



mented processes, tactile in 



function, which both in 



their appearance and their 



use resemble antennae ; (ii) 



the three, paired elements 



of the ovipositor, which is 



developed in the females of 



certain Thysanura, Orthop- 



tera, Odonata, Hemiptera, 



Physapoda and Hymeno- 



ptera, in which last named 



order the ovipositor is often 



modified to form a saw or a 



sting. It is formed, gen- 



erally speaking, from 



processes of the seventh, 



eighth and ninth abdominal 



segments, though in many 



cases it appears that the 



posterior two pair of pro- 



cesses arise together from 



the ninth (Fig. 379) ; (iii) 



certain daspers and other 



processes connected with 



the male intromittent 



Organ and With Copulation (after L6onDufour). Sp salivary glands ; Oe oeso- 



phagus with crop-like dilatation ; M chyliflc ven- 



which Seem to have an tricle ; Re malpighian vessels ; R rectum with 



so-called rectal glands ; G. Dr poison glands: 



origin similar to that 01 



the component parts of the ovipositor with whose claim to be 



regarded as true appendages theirs must stand or fall. 



The Alimentary Canal. Embryologically the alimentary 

 canal is divided into (a) the stomodaeum or fore-gut which gives 

 rise to (i) the mouth and pharynx, (ii) the oesophagus (Fig. 380), 

 (iii) the crop, (iv) the proventriculus or gizzard ; (b) the mesen- 



Q.Vr: 



FIG. 380. Digestive apparatus of Apis mellifica 



6onDufour). Sp salivary glands ; 

 phagus with crop-like dilatation 



