THE ABDOMEN. 113 



placed together, exactly correspond, and form a single organ the 

 ovipositor. Between them lies the female sexual aperture, and the 

 eggs are laid encompassed by them. (Locusta.} 



Besides the above-named organs, several other forms are observed at 

 the apex of the abdomen, which neither belong to the anus, nor can be 

 considered as standing in connection with the sexual organs. They 

 bear the general name of TAIL (cauda) or CAUDAL, APPENDAGES 

 (Appendices caudales) : as such we may consider 



The FORCEPS (forcipes, PI. XIV. f. 8), two toothed cheliform 

 hooks, which move in opposition to each other, in the earwig. 

 (Forficula.} 



The FORK (furca, PI. XIV. f. 9) a continuation of the lower 

 portion of the terminal segment, which is directed forwards, and is 

 furcate, by means of which the insect springs upwards. (Podura, 

 Smynthtirux.') 



The STYLES (styli, PI. XIV. f. 10), two short exarticulate processes, 

 close to the anus in Staphylinus. 



The CERCI (cerci, PI. XIV. f. 11), likewise short, lanceolate, and 

 generally flattened and articulate appendages at the sides of the anus. 

 (Blatta.) 



The THREADS (fla, PI. XIV. f. 12), longer or shorter articulate 

 cylindrical processes of the last segment, which grow gradually thinner. 

 (Acheta, Ephemera, Lepisma.) 



The BRISTLES (setts, PI. XIV. f. 13) are such appendages when 

 exarticulate and simple. (Mackilis.) 



The SIPHONETS (siphunculi, PI. XIV. f. 14) are the hollow processes 

 upon the upper side of the penultimate segment in the plant-lice (Aphis), 

 whence the sweet juice exudes which the ants seek so eagerly. 



