142 The Naturalist in La Plata. 



blade of grass has its colony ; clusters of hundreds 

 adhere to the twigs ; myriads are found in the bush 

 clumps. Lean and flat when growing to the leaves, 

 the tick catches man or beast brushing by, fattens 

 rapidly, and, at the end of a week's good living, 

 drops off, plena cruoris." When on trees, Belt says, 

 they instinctively place themselves on the extreme 

 tips of leaves and shoots, with their hind legs stretch- 

 ing 1 out, each foot armed with two hooks or claws, 

 with which to lay hold of any animal brushing by. 



During this wretched, incom- 

 AjX ■cvLjfri" plete existence (from which, in 



J&\~ jfPvK~ mos ^ cases J it is never destined 



to emerge), its greatest length 



is about one-fourth of an inch ; 



but where it fastens itself to an 

 Ixodes a i wood dief aft6r animal the abdomen increases to 



a globe as big as a medium-sized 

 Barcelona nut. Being silvery-grey or white in 

 colour, it becomes, when thus distended, very con- 

 spicuous on any dark surface. I have frequently 

 seen black, smooth-haired dogs with their coats 

 turned into a perfect garden of these white spider- 

 flowers or mushrooms. The white globe is leathery, 

 and nothing can injure it ; and the poor beast 

 cannot rub, bite, or scratch it off, as it is anchored 

 to his flesh by eight sets of hooks and a triangle 

 of teeth. 



The ticks inhabiting regions rich in bird and 

 insect life, but with few mammals, are in the same 

 condition as mosquitoes, as far as the supply of 

 blood goes ; and, like the mosquitoes, they are com- 

 pelled and able to exist without the nourishment 



