50 COMMON BRITISH INSECTS. 



disc. There is a reddish-yellow triangular mark on 

 the forehead, and a very slight ridge on the crown. The 

 thorax is blacker than the elytra, and, like them, has 

 the margin yellow. 



The legs of this Beetle are excellent examples of 

 these limbs as they are modified in the Hydrade- 

 phaga. Both the middle and hind pairs of legs are 

 flattened, oar-like, and furnished with the bristle 

 blade, and the coxa is so made that it only allows 

 one kind of movement to the limb. In consequence 

 of this peculiarity the Dyticus cannot walk properly, 

 but only scrambles about ; and if it should by chance 

 fall on its back on a smooth surface, it spins round 

 and round in a most ludicrous fashion. 



The first pair of legs, however, are the most inter- 

 esting. We have already seen that, in very many 

 Beetles, the tarsi of the front pair of legs are dilated 

 in the male, but there are none which even approach 

 those of the Dyticus in complexity of structure. The 

 geodephagous males have the under sur- 

 face of these dilated joints merely furnished 

 with a pad, but the Dyticus has a most 

 wonderful array of suckers, exactly ana- 

 logous in principle to those which stud the 

 arms of the cuttle-fish. One of the legs is 

 ante- nere snown - The three basal joints of the 

 tarsus are enormously swollen, so that 

 they assume a plate-like shape. Their upper surface 

 is smooth enough, but the under surface is covered 

 with suckers, one of them very large, and the second 

 about half its size, and a multitude of smaller suckers. 

 The larger suckers are placed directly upon the joint. 



