490 



HYMENOPTERA 



thereto. 



It exhibits, however, considerable variety, and is seen 

 in its simplest and least soldered state in 

 CeiJhus. In the higher bees the pro- 

 notum takes on a form not seen in any- 

 other Insects, being one of the most 

 beautiful sclerites to be found in the 

 class (Fig. 334, pronotum of Xylocopa). 

 "We have already remarked that in 

 Hymen op tera the lower portions of the 

 prothoracic segment are detached from 

 the upper, so 

 that the pro- 

 notum is not 

 supported be- 

 neath by a 

 sternum as 



usual. In the Yw. 334.— Pronotum of a car- 

 bees in OUeS- peuter bee, Xylocopa sp. 



^ ^ East India. 



tion the pro- 

 notum makes up for the removal of the 

 corresponding side -pieces and sternum. 

 Fig. 333.-Aiitriink of Sphex '^J becoming itself a complete ring, 

 chnjsis. A, Dorsal aspect : ^^^ gj^ies being prolonged and meeting 



a, pronotum ; 6, mesouotum ; . • n n i- /■ j_i 



c,teguia; rf, base of anterior, lu the middle line 01 the under sur- 



of posterior, wing ;/, 5., ^^^^ ^f ^.J^g -^^^^^ ^^ ^J^g g^j^^g ^^^^ 

 ivisious of metanotum ; //, ^ 



a large lobe is developed laterally on 

 each side, overlying and protecting the 

 first breathing orifice. The intermediate 

 Llmi;t.°\!"errt! stages of this remarkable modification 

 pect of tiie median seg- may be observed by dissecting a small 



ment : a, upper part ; b, ■ /. r i 



superior, c, inferior abdomi! scnes of genera of bees. 

 nai foramen ; d, ventral Although the prostemum of a Hymen- 

 plate of median segment : , t- . ■ , n • -i 1 



e^ coxa. opterous insect is not usually visible 



owing to its being overwrapped by the 

 side-pieces, it is really, as shown in Fig. 335, B, of complicated 

 form. In Civibeo: and some other sawflies the side-pieces are not so 

 large as usual, but the prosternuni is larger and is exposed. The 

 prothoracic spiracle is rarely visible externally, but its position 

 is remarkably constant, and is usually indicated by a peculiar 

 lobe or angle of the pronotum projecting backwards just below 



divisions i 

 median (true first abdomi- 

 nal) segment ; 2, its spir- 

 acle ; /,-, second abdominal 

 segment, usually called the 



