710 EXTERNAL ANATOMY OF INSECTS. 
Evania ; conical in Celyoxis; rhomboidal in many 
Mantes ; boat-shaped in many Lygei ; fusiform in va- 
rious Papilionide ; lanceolate in some Ichneumonidae, 
falcate in others; nearly round in Diapria purpuras- 
cens; ovate in Lyrops; elliptical in Andrena ; oblong 
in many Xylocope ; heart-shaped in the naked Eugios- 
se; triangular in Dytiscus; gibbous in Flata; and 
vaulted in Chrysis. At its base it is truncated in Szrez ; 
retuse in most bees ; forming the segment of a circle in 
Andrena ; in general sessile, but in the majority of Hy- 
menoptera, as has been already observed, terminating in 
a pedicle. The pedicle is very short in the Andrenide 
and Apide ; long in the Sphecide ; thick in the Form- 
cide ; slender in Evania ; fusiform in Pelecinus ; cla- 
vate in Ammophila; campanulate in many Vespide ; 
nodose in Myrmica* ; squamigerous in Formica: it 
sometimes also consists of ¢wo joints, as in Ammophila 
and many Vespide. As to margin, some have none, as 
Centrotus; in others, as Dytiscus, it is very narrow; 
in others again, wide and flat, as in the Nepide; in Sta- 
phylinus, &c., it is distinguishable only on the upper 
side of the abdomen; in Locusta Leach only on the un- 
der side, though mostly intire; it is serrated in Blatta, 
sinuated in Coreus paradoxus, and crenated in Cerceris. 
v. Proportions. ‘These vary greatly in the different 
tribes ; in some the abdomen is long and slender, as in 
Locusta and Staphylinus ; disproportionably so in a re- 
markable degree in some Agrionide from South America, 
as A. lineare, &c.°; in others it is extremely short and 
2 Prove [X, Bic ai6. I’. » Jbid. Fic. 17. H’. 
© Roemer, Genera, &c. t. xxiv. f. 4. 
ED OLE cE OE 
