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 t, the inner lobe, and ie, the exte- 
rior lobe representing the galea ; c, the stipes ; d, the cardo ; 
p, the palpus (six-jointed.) — Fig. 16, the labium ; — m «, Che 
inentum ; l 2, the trilohed labium ; l p, the labial palpus. 
Fig. 17, the maxillae and labrum of Sirex Juvenous (male;) 
m «r, maxilla maxillarv palpi ; a , the fulcrum ; m 
», the mentum ; l 2, the lower lip ; l p , the labial palpi. 
Figs. 18-23, oral organs of a Pimpla, — Fig. 18, the head seen 
from the front ; — cr, antenna ; e e y the eyes ; o, ocelli ; l i, the 
minute upper lip ; m % the mandibles ; m j- p, maxillary palpi ; 
Ip , labial palpi. — Fig. 19, head seen from behind ; — m n, 
the mentum ; l 2, the labium ; m j 1 , the maxilla*; m vp, the 
maxillary palpi ; Ip, labial palpi Fig. 20, labrum; — 1 1, 
the appendiculata (Kirby and Spence.) — Fig. 21, one of 
the bifid mandibles. — Fig. 22, maxilla; — l e , external 
lobe; / *, internal lobe; c, stipes; d , cardo; p , maxillary 
palpus. — Fig. 23, lower lip; — a, fulcrum; m n, mentum; 
l 2, labium ; l p, labial palpi. 
The variations of the antennas are too numerous 
to be specified in this place. The number of joints is 
from three (their amount in Hylotomd) to about fifty. 
These multiarticulate antennae are chiefly to be found 
among the Ichneumonidae, whose economy renders 
it necessary that they should be very flexible for the 
purpose of exploring the holes and crcviccs into 
which they introduce their eggs. In some instances 
the antennae are bipectinatcd ; in other cases (as in 
Cryptus ) they appear double, the third joint being 
long and furcate. They are often very dissimilar in 
