CHAPTER XX 



PENTASTOMIDA ^ 



OCCURRENCE ECONOMIC IMPORTANCE — STRUCTURE 



DEVELOPJVIENT AND LIFE-HISTORY SYSTEMATIC 



Pentastomids are unpleasant -looking, iluke-like or worm-like 

 animals, which pass their adult lives in the nasal cavities, 

 frontal sinuses, and lungs of liesh-eating animals, such as the 

 Carnivora, Crocodiles, and Snakes ; more rarely in Lizards, Birds, 

 or Fishes. From these retreats their eggs or larvae are sneezed 

 out or coughed up, or in some other way expelled from the 

 body of their primary host, and then if they are eaten, as 

 they may well be if they fall on grass, by some vegetable-feeding 

 or omnivorous animal, they undergo a further development. If 

 uneaten the eggs die. When once in the stomach of the second 

 host, the egg-shell is dissolved and a larva emerges (Fig. 260, 

 p. 494), which bores through the stomach- wall and comes to rest in 

 a. cyst in some of the neighbouring viscera. Here, with occasional 

 wanderings which may prove fatal to the host, it matures, and 

 should the second host be eaten by one of the first, the encysted 

 form escapes, makes its way to the nasal chambers or lungs, and 

 attaching itself by means of its two pairs of hooks, comes to rest 

 on some surface capable of affording nutriment. Having once 

 taken up its position the female seldom moves, but the males, 



^ Tlie animals included in this group are usually called Linguatulidae or 

 Pentastomidae after the two genera or sub-genera Linguatula and Pentastoma. 

 But the animal which Rudolphi in 1819 {Synopsis Entozoorum) named Fcntastoma 

 had been described, figured, and named Forocephalus by Humboldt {Recucil 

 d' observations de zoologie et anatomie comparee, i. p. 298, pi. xxvi.) in 1811. The 

 fiimiliar name Pentastoma may, however, be preserved by incorporating it in the 

 designation of the grouji. 



