CETONIIN.i;. 



27 



some Cremastochilini and Valgini is very broad and serves to 

 enclose and protect the sensitive parr of the organ when the head 

 is folded beneath the thorax. 



Sexual Dimorphism. 



In several genera the male bears a pair of horns or antlers upon 

 the head, and there are a few (although at present no Indian 

 representative is known) in which a single horn is borne upon 

 the prothorax. In Trigonoplwrus both sexes bear a process at 

 the front of the clypeus and another process upon the forehead 

 the latter differing' in male and female; while in Heterori-hina an 

 appendage is always found upou the forehead in the female, but 

 not always in the male. Much more frequent sexual differences 

 are found in the structure of the legs. I have already remarked 

 that these are almost always used in the female for digging. The 

 front tibia is of chief importance for this purpose, and is accord- 

 ingly strong and armed externally with teeth, generally three m 

 number. In many males this function does not exist, and the 

 tibia is less stout and strong and the teeth reduced or quite absent. 

 In some, such as Jumnos rucheri (PI. I, fig. 6), the whole leg is 

 greatly elongated and the tibia is fantastically toothed on the lower 

 surface. The tarsi are very often more slender in the male than m 

 the other sex. On the other hand the hind legs are sometimes 

 stronger in the male than in the female, as in Eucliloropus lintus. 

 A shght but peculiar feature is often found in the two spines at the 

 end of the hind tibia, which are commonly short and sharp in the 

 male, and longer and blunter in the female. Elongation of the club 

 of the antenna, very general in the males of other subfamilies, 

 is rare in the Ceioniin^. The form of the abdomen very 

 frequently differs, the males having the lower surface arched or 

 even deeply hollowed out along the middle. In females of Vahjus 

 and Charitovalfjus the end of the abdomen gives rise to a long 

 slender style suggestive of the ovipositor of Hymenoptera and 

 other insects. 



Differences of colour and pattern also occur, althoughthey are 

 less common than structural differences. Generally their nature 

 has been overlooked and the two sexes have been described as 

 distinct species, as in various members of the genera Macronota 

 and Glyaipliana. In such cases the male is usually brightly 

 coloured and the female dull and undistinguished. Thus in 

 Macronota crucicollis and oherthuri, two South Indian species, the 

 males are red or black, decorated with an elaborate pattern of 

 white lines, while the females are coloured auuiform clayey-brown. 

 In the North-Indian Heterorrliina mutahilis and ff. dispar, the males 

 are resplendent in exquisite shades of green, blue or purple, and 

 the females an unpleasing dull brown or black. In some of the 

 Valgini, in which the markings are due to the arrangement of 

 different coloured scales, the colours are also different in the two 

 sexes, and here again the males have brighter and more varied 

 colours. 



