CHAPTER Vm. 

 STERNOXI. 



The group that now comes before us is a very boldly marked 

 one, and yet has been described under more than one title. 

 Some entomologists have selected the word Serricornes, or 

 ' saw-horned,' because the antennae are serrated, i.e. notched, 

 like the teeth of a saw, two examples of which may be seen on 

 Woodcut XIII. Figs, a and c. As, however, so many Beetles 

 that do not belong to this group have their antennae serrated, 

 the word has been abandoned in favour of Stemoxi^ or ' sharp- 

 breasted,' because the presternum, or under side of the thorax 

 (see Woodcut I. Fig. 8), is prolonged backwards with a sort of 

 spike, which fits into a cavity between the middle pair of legs. 

 This projection is technically named the ' mucro,' or dagger. 

 The body is long, rather cylindrical, but slightly flattened, and 

 the antennae are mostly serrated, but sometimes pectinated, 

 and in a few instances nearly plain and thread-like. There 

 are other distinctions, but these are so bold and evident that 

 they will be quite sufficient for the reader's purpose. 



Most of these insects possess the curious power of leaping, 

 which has earned for them the popular title of Skipjack Beetles. 

 Their legs are very short, so that if the Beetle should by any 

 chance fall on its back on a flat surface, it would have no 

 power of recovering itself, but for the curious piece of me- 

 chanism of which the ' mucro ' forms a portion. Whenever 

 the Beetle falls on its back, and cannot recover itself, it lies 

 still for a few moments, and then begins to arch its body, so 

 that it rests only upon the end of the abdomen and the back 

 of the head, the thorax being well elevated. By this move- 

 ment, the mucro is drawn out of the groove into which it fits. 

 Suddenly, the insect reverses its position and springs the elastic 

 mucro into its place, thus driving the base of the elytra against 

 the ground, and causing itself to fly up into the air. 



