270 NATURAL ARRANGEMENT OF INSECTS. 



colour harmonises with their form, to make them hideous, 

 for they are invariably of a deep black or dirty brown. 

 Epiphysa offers us the most gibbous form amongst 

 them. In Cryptocheile and Adesmia, this form is 

 covered with short spines or tubercles, placed either 

 irregularly over the whole surface, or arranged in rows 

 between which there are furrows. In Pimelia proper, 

 and Moluris, we have the gibbous form also greatly 

 developed, but with a deep strangulation between the 

 thorax and abdomen : and in Prionotheca, the same 

 general form is somewhat flattened, and the lateral su- 

 perior edges of the elytra are armed with a coronet of 

 protruding spines. In others, we observe them taking 

 the more general figure of Carabida, as in Scaurus and 

 Trachynotus ; and in others again they become exceed- 

 ingly flattened with dilated edges, as in Eurychora; and 

 which, in Steira, is furnished above with longitudinal 

 carinse. Among the aberrant forms, we may notice the 

 extraordinary Helens, which is very like a black Cassida, 

 with a perforation through the dilated margin of the 

 thorax, for the head to exhibit itself; and in one species 

 the whole of the central convex portion of the insect is 

 covered with erect rigid setae ; and amongst the most he- 

 terogeneous of these forms, Machla claims a place. The 

 affinities of this group to the circle are obscure, and 

 difficult to trace; their position is suggested for the ana. 

 lytical examination of entomologists. 



(237.) The Staphylinida, or rove beetles, constitute 

 our fifth group of predatorial insects : their distinguish- 

 ing characteristic, as we have above said, is to have 

 considerably abridged elytra, beneath which their ex- 

 pansive wings are folded up ; and thus there are almost 

 always more, and never fewer, than four segments ex- 

 posed. As in the Coleoptem generally, their antennae 

 consist of eleven joints, rarely of ten, and the apex of 

 their abdomen is usually furnished with a couple of 

 retractile vesicles. There is great diversity in the 

 number of the joints of their tarsi, but the typical 

 number may be considered as five. They are exces- 



