DYNASTIN^. 257 



enlarged at the expense of the pygidium, as in the genus Dipelicus 

 (see fig. 76) ; in another group {Heteronychus, etc.) the ridges 

 are restricted to two longitudinal lines near the middle of the pro- 

 pygidium. Some species, which do not possess the apparatus in 

 either form, nevertheless produce a considerable volume of sound 

 by movements of the abdomen similar to those by which the 

 stridulating ridges are brought into opei'ation. Air is apparently 

 imprisoned between the elytra and the back and then expelled 

 with some force, producing a hissing sound. In the large and 

 common Xylotrupes gideon this has often been observed. 



The occurrence of horns, even of the largest size, upon the head 

 is not accompanied by a corresponding development of the head 

 itself, which, on the contrary, is relatively smaller than in the 

 Cetoniin^. The clypeus is genei'ally small and the eyes less 

 prominent than in the previous group, being divided in front 

 by a ridge which forms a lateral extension of the clypeus. The 

 antennae are inserted beneath this ridge and consist of ten 

 joints, of which three form the club. They show little variation 

 throughout the Subfamily, nor do they appreciably differ in the 

 two sexes. 



The mandibles are much more developed than in the Cetoniin^ 

 and, except in certain forms not represented within the Indian area, 

 are always in part visible from above (i. e. produced beyond the 

 margins of the clypeus) and generally notched or lobed at the 

 outer edge. The maxillae are generally furnished with several sharp 

 strong teeth and closely fringed with stiff hairs. The mentum 

 and ligula are fused together and the labrum small, membranous 

 and concealed. 



The legs are inserted in a rather different manner to that found 

 in the Cetoniin^. The front coxae are more deeply imbedded in 

 the thorax, broad and transverse, and the prosternum forms a 

 process behind them which is sometimes free and columnar, 

 sometimes inclined and in close contact with the coxae. All the 

 coxae ai-e contiguous in the middle, so that the mesosternum is 

 divided from the metasternum and the two parts do not produce 

 in the middle a process pointing forward as in most CetoniintE and 

 many Eutelin^ and Melolonthin^. The legs differ considerably 

 in form. Some genera, apparently with more than the normal 

 digging powers, have them extremely short, with very thick and 

 muscular femora and tibiae, the latter generally trumpet-shaped 

 and their wide extremities fringed with very strong spines, and the 

 tarsi tapering and very slight at the end. The rest have the legs 

 of moderate length, and the tarsi slender and uniform. The front 

 tibia has always three stout external teeth and there are sometimes 

 four or more, in which last case smaller teeth appear between the 

 three primary ones. The claws are always simple, symmetrical and 

 immovable, except upon the foi-e-feet of the males in certain 

 genera. 



8 



