444 EXTERNAL ANATOMY OF INSECTS. 



lobe also in this tribe varies as little as the upper, being 

 shaped like the last joint of that lobe in Cychrus just de- 

 scribed, except that in Cicindela it is narrowest in the 

 middle a . In other tribes the upper valve is sometimes 

 linear and rounded at the apex, and the lower truncated, 

 as in Staphylinus olens b ; sometimes the upper one is 

 truncated or obtuse, and the lower acute, as in Trogosita 

 and Parnus c . In Ptinus, another tribe of beetles, be- 

 fore noticed as injurious to our museums d , the reverse of 

 this takes place, the upper-lobe, which is the smallest 

 and shortest, being acute, and the lower truncated e . In 

 Blaps both are acute f . In Rhipiphorus and Scolytus the 

 lobes are nearly obsolete. The lower lobe is bifid in 

 Languria, a North American genus of beetles, so as to 

 give the maxilla the appearance of three lobes s ; and in 

 Erotylus, a South American one, the upper is triangu- 

 lar 11 : it is often oblong, quadrangular, linear, &c. in 

 others. — In those that have only one lobe the shape also 

 varies. In Gyrinus, the beetle that whirls round and 

 round on the surface of every pool, which, though it be- 

 longs to the Predaceous tribe, has only one lobe, the lobe 

 represents a mandible in shape of the laniary kind, being 



merous one yet undiscovered, as Calosoma is of Adelium (Kirby Linn. 

 Trans, xii. t. xxii./. 2.) 



a Clairv. Ent. Helvet. ii. t. xxiv. /. super, b. 



"> Plate XXVI. Fig. 11. 



c Oliv. Ins. no. 19. Trogosita. t. 1./. d. no. 41 bis. Dryops. Li. 

 /.I.e. cI See above, Vol. I. p. 238. 



e Oliv. Ins. no. 17. Ptinus. t. i.f. 1. c. 



i Ibid. no. 60. Blaps. t. i.f. 2. c. 



E Ibid. no. 88. Languria. t. i.f. 2. c. 



h Ibid. no. 89. Erotylus. t. ii./. 12. c. 



