298 SYSTEMATIC ARRANGEMENT 



in most of the other orders, and all the accessory parts 



are strongly developed. 



These, and other parts of the oral appendages, 



are represented on PI. XXVI. 



Figs. 15 and 16, the maxilla and labium of a Tenthredo 



Fig. 15, the maxilla ; 1 , the inner lobe, and I e, the exte- 

 rior lobe representing the galea ; c, the stipes ; c?, the cardo ; 

 p, the palpus (six-jointed.) Fig. 16, the labium ; -m , the 

 mentum ; I 2, the trilobed labium ; / />, the labial palpus. 



Fig. 17, the maxillae and labrum of Sirex juvencus (male ;) 

 77i <r, maxillae ; in a; p, maxillary palpi ; a, the fulcrum ; m 

 TZ, the mentum ; I 2, the lower lip ; I JP, the labial palpi. 



Figs. 18-23, oral organs of a Pimpla Fig. 18, the head seen 



from the front ; o, antenna ; e e, the eyes ; o, ocelli ; I i, the 

 minute upper lip ; m, the mandibles ; m xp, maxillary palpi ; 



lp, labial palpi. Fig. 19, head seen from behind; m , 



the mentum ; I 2, the labium ; m a?, the maxillae ; m or p, the 



maxillary palpi; I p, labial palpi. Fig. 20, labrum; / 1, 



the appendiculata (Kirby and Spence.) Fig. 21, one of 

 the bifid mandibles Fig. 22, maxilla ;-^-Z e, external 

 lobe ; 1 1, internal lobe ; c, stipes ; c?, cardo ; jo, maxillary 

 palpus Fig. 23, lower lip ; a, fulcrum ; m n, mentum ; 

 I 2, labium ; I jo, labial palpi. 



The variations of the antennae are too numerous 

 to be specified in this place. The number of joints is 

 from three (their amount in Uylotoma) to about fifty. 

 These multiarticulate antennas are chiefly to be found 

 among the Ichneumonidse, whose economy renders 

 it necessary that they should be very flexible for the 

 purpose of exploring the holes and crevices into 

 which they introduce their eggs. In some instances 

 the antennee are bipectinated ; in other cases (as in 

 Cry plus) they appear double, the third joint being 

 long and furcate. They are often very dissimilar in 



