LTNGUATULIDA 



733 



The mouth is situated anteriorly, and is either terminal or sub- 

 terminal, with a chitinous ring. Two pairs of chitinous hooks, 

 retractile into grooves, are situate on either side of the mouth, and 

 are looked upon by Stiles as antennae and palpi. There are no legs. 

 The anus is terminal at the posterior end of the abdomen, with the 

 female aperture situate just in front. The male generative pore 

 is on the ventral surface, near the anterior end of the abdomen. 

 The sexes are distinct. The mouth leads into a simple straight 

 alimentary canal, which ends in the anus. There are no circula- 

 tory or respiratory organs. The nervous system consists of a ventral 

 mass and a circumoesophageal commissure. 



Life-History. — -The female produces eggs, which, escaping from 

 the definitive host, pass into the intermediary host, and there hatch 

 out a four-legged larva, not unlike an embyro Acarus. TKis embryo 

 undergoes complete metamorphosis, and forms a n57mph resembling 

 the adult, which does not, as a rule, mature, until it reaches its 

 definitive host again. 



Genera. — -Linguatula Frblich, iy8g;Porocephalus Humboldt, 1811; 

 ReighardiaWsiTd, 1899; and Raillietiella Sambon, 1909; but only the 

 first two contain species parasitic in man. 



Linguatula Frolich, 1789. 



Linguatulida with depressed body, rounded dorsum, and crenat^^ 

 margins. Body cavity forming diverticuli into the lateral parts 

 of the rings. 



Specles.—Linguatula serrata Frolich, 1879. 



Linguatula serrata Frohch, 1789. 



Synonyms. — -TcBnia rhinaria Pilger, 1802; Polystoma tcenioides 

 Rudolphi, 1810; Linguatula tcenioides Lambinet, 1816; Pentastoma 

 tcenioides Rudolphi, 1819. Nymph. — Pentastoma dentimlatum. 



The adult lives in the nasal cavity and frontal sinus of the dog, 

 wolf, fox, and rarely in the horse, mule, sheep, goat, and man in 

 Europe; while the larva exists in sheep, oxen, horses, rarely in cats 

 and dogs. Its real host appears to be the dog, especially sheep-dogs. 



Habitat. — -Europe, especially Central France. 



Morphology. — -The male is white in colour, 18 to 20 millimetres 

 in length, and 3 millimetres broad. The female is greyish-white 

 or brownish, owing to the contained ova. 



Life-History.— The eggs, which are ovoid, 90 by 70 jj,, are laid in 

 the nasal cavities of the dog, and expelled by sneezing. If they 

 fall on grass, they may enter the alimentary canal of a herbivorous 

 animal, in whose intestine the embryo hatches. This embryo 

 measures 130 by 60 and possesses two pairs of legs and an anterior 

 perforating apparatus composed of a stylet and two hooks. 



It now bores its way into the liver, lungs, or some other organ, 

 and in about eight weeks becomes encysted, losing all its appendages 

 and measuring 275 by 180 



