We have first to speak of the Chigoe, an insect, the female of which alone demands lodging and provisions, the male being contented, like those of the preceding chapter, with pillaging his victim as he passes by. This parasite of man inhabits South America, and has received the name of _Pulex penetrans_, or, according to the latest nomenclature, of _Rhyncoprion penetrans_. It is a very small species, which pierces the shoes and the clothes with its pointed beak (Fig. 27), and penetrates into the substance of the skin; the male (Fig. 26) is contented with sucking the blood, and then resumes its wanderings, like the parasites of which we have spoken in the preceding chapter; while the female finds for herself a hiding-place, and becomes of such 142 a monstrous size that the entire insect is nothing more than an appendage of the abdomen, as may be seen in the annexed figure. This insect is well known, since it attacks man, and usually establishes itself on his toes, but it occasionally fixes itself in the same manner on the dog, the cat, the pig, the horse, and the goat. It has also been seen upon the mule. Mons. Guyon has paid much attention to it, but we owe the last observations to Mons. Bonnet, a French navy surgeon, who passed three years in Guiana, and has ascertained that the chigoe fortunately does not extend beyond the 29th degree of south latitude. Another parasite, well known by sportsmen, is the tick. It is not an insect like the flea, but an arachnid, a kind of acarus, which passes through its last stages of development under the skin of a mammal. It is called _Ixodes ricinus_, and Professor Pachenstecher has carefully studied its organization. The ticks especially attack dogs, but are also found on the roebuck, the sheep, the hedgehog, and even on bats.