164 



THE BRITISH NATURALIST. 



[AuGUSx 



sexual modification. Thus while the male of Cevcus pediciilarius has 

 the first two joints widened, that of C. bipustalatus has only the first 

 enlarged, the females of both these species having the joints unaltered 

 — and scarcely distinguishable from each other ; the males of 

 Bafrisns have the first two joints of the antennae longer than in the 

 females. The genus Bythinus presents some curious alterations in the 

 basal joints, m the male alone : B. puncticoilis has the two basal joints 

 thickened, and tlie first joint has a tooth on the inner side; B. curtisii 

 has the second joint globular with a similar tooth ; B. secuviger 

 and hurrelli have the first joint cylindrical and while in the 

 former the second is very broadly hatchet-shaped, in the latter this 

 joint is like a new moon with the horns projecting inwards. Homalota 

 coriaria has the second and third joints of the male antenna furnished 

 with long hairs, while several of the same genus [pagana, oblongiusnila 

 occulta, picipes, &c.) have the third joint thickened (stouter) in the 

 male. Apion dijfonne has, in the same sex, the third and fourth joints 

 very much broader than the rest. The genus Phyllotreta contains 

 several species m which the fourth and fifth joints or (ochripes) the 

 fifth alone is stouter in the male ; this sex of Tychus nigcr has the fifth 

 joint three times broader than either the fourth or sixth ; while 

 Agrilus laticornis has the whole of the middle joints strongly widened 

 in the male, and the same sex of the water beetles Noteriis clavicovnis 

 and spavsiis have the whole antennae greatly, but regularly thickened — 

 those of the female being simple. The most singular modifications 

 in the antennae are seen in the males of some species of Malachius 

 and Meloe — modifications believed to be intended to assist 

 in the capture of the female and for holding her during the act of 

 sexual union. In Malachius csiieiis the second joint of each antenna 

 projects inwards, and the third is furnished with a long hook, which 

 nearly meets the prominent second ; in M . bipustnlatus the second 

 joint has a broad prominence, the third has a large tooth, the fourth 

 has a hook nearly meeting the second, and the fifth is swollen ; M. 

 margincUus has the third, fourth, fifth, sixth, and seventh joints 

 hollowed out on the inner-side, the ends of the joints forming projecting 

 teeth ; while the male of J/, viridis has the antennae quite simple. 

 In the males of several species of Meloe {e.g. M. pvoscafahmis) the 

 third, fourth, and fifth joints are somewhat dilated, the sixth and 

 seventh are flattened, joined by their edges, and so hollowed out on 

 the inside as to give the organ the appearance of having been 

 broken and badly rejoined — the antennae of the female being quite 

 simple. The last peculiarity to be mentioned here occurs in the 

 males of several species of Telephorus (lividus, pellucidiis, nigricans, 

 obscums, bicolor, &c.J, where the middle joints of the antennae, 

 usually the fourth to the tenth, have a very fine groove or impressed 



