216 



The point to which I wish to direct your attention is, that in 

 this particular instance there would be no use whatever in a 

 claw or claws which moved merely up and down in reference 

 to the position of the body, or which approached each other 

 laterally. The habits of the insects are to creep upon the 

 surface of clear water, and to shun all those parts covered 

 with weeds or floating leaves — below the surface it is 

 probable they cannot immerse their claws. 



To be of any service, therefore, the last joint must be as it 

 were half twisted round, so that the claws may be serviceable 

 in removing any floating substance out of their way. 



This we find to be actually the case ; the foot consists of 

 two hooks faintly curved, arranged perpendicularly to the 

 water. 



A small brush of hairs is below them — nearest the surface 

 of the water — which would effectually remove any small body, 

 leaving the larger ones and those which rose higher from the 

 water to be removed by the hooks. 



Both the hooks and brushes are, as we might imagine, di- 

 rected backwards, so as to act in the most advantageous way 

 for the insect's progression. 



The simple pair of hooks exists chiefly in the tribes of in- 

 sects of the Coleopterous order. They may be found in many 

 others, but it is unnecessary to particularize them. 



I have not thought it necessary to make a separate diagram 

 of them, as they do not essentially differ from those associated 

 with membranous flaps. I may just remark, en passant, that 

 all the larger claws are found to be hollow in their interior, 

 and that all, with few exceptions, are covered with hairs of 

 variable size. 



The intention of the hoUowness of the claw is evidently to 

 give it as much lightness as is compatible with strength. 



We may well suppose that the weight would be, compara- 

 tively speaking, enormous, were the whole of the sohdity and 

 consistency of the tip. 



