286 THE BIOLOGY OF INSECTS 



are furnished with a remarkable hairy covering which 

 probably assists them to secure air-bubbles for breathing 

 when submerged. The leaf-beetles of the Donaciine group, 

 whose adaptations for aquatic hfe have been described, 

 have a species, Ilaemonia curtisi, which lives always in 

 brackish water, feeding on the Sea-wrack (Zostera) and 

 breathing in the same way as its relations do on the water- 

 lilies and other plants of ponds and streams. Some of the 

 marine ground-beetles (Carabidae) are of especial interest. 

 All beetle-collectors know many species of Bembidium, 

 usually small dark beetles that lurk in damp places, several 

 haunting the sea-shore above high-water mark. Cillenus 

 lateralis is an allied form, wingless with bronzy green head 

 and thorax and sandy wing-cases found on the sand or among 

 stones between tide-marks from the British and Dutch 

 coasts southwards to North Africa. They run in the sun- 

 shine on the expanse left by the ebbing tide ; when the 

 water comes in they seek shelter under stones or burrow in 

 the sand. They have relatively powerful and sharp 

 mandibles and prey on the sandhopper Talitrus, as A. H. 

 Haliday observed ninety years ago (1837), '' seizing them 

 by the soft part of the under side, and in this way are able 

 to master game many times their own bulk. Sometimes 

 three or four beetles may be found in concert attacking 

 a sandhopper of the largest size. The tide returning has 

 scarcely uncovered the sand when these little depredators 

 are abroad from their hiding-places and alert in the chase." 

 But the tiny beetles of the genus Aepus only 2 mm. (jVi^-) 

 long are perhaps the most remarkable marine insects of 

 the whole order ; they may be recognised by the relatively 

 enormous head, the broad truncated abdomen and the short 

 wing-cases, wings being quite absent. Our two British 

 and Irish species, A. mariniis and A. robini, range south to 

 Spain and out to the Madeiras. The widened fore-shin 

 has a comb-bearing notch for cleaning the feelers from 

 grains of sand. The long, bristly hairs serve to entangle 

 air-bubbles when the beetles are submerged, as w^as first 

 noticed by J. V. Audouin (1833). '' If," he wrote, '' one 



