LINGUATULA RHINARIA 387 



Order Linguatulidce (Tongue Worms). 



Arachnoidea greatly altered in consequence of their parasitic manner of 

 life ; for a long time they were regarded as Helminthes. The body is elongated, 

 vermiform, flattened or cylindrical, and more or less distinctly annulated. 

 The head, thorax, and abdomen are not denned from each other (fig. 249). 

 The elliptical mouth, surrounded by a chitinous ring, is situated at the 

 anterior end, on the ventral surface, and the intestine leading straight 

 through the body opens at the posterior end. Two hooks, retractile into 

 grooves, are set at both sides of the mouth (fig. 250) ; these are usually 

 considered to be the terminal joints of two pairs of legs, but it appears 

 to be more correct to regard them as the remains of the antennae and" 

 palpi (Stiles). According to this opinion, the legs in the adult state would 

 be completely degenerated. 



The nervous system is reduced to an ossophageal ring. No organs of 

 sense are recognisable except the papillae at the anterior end. There are 

 neither organs of circulation nor respiration. 1 



The sexes are distinct. In the small male the sexual orifice is situated 

 ventrally in the anterior part of the body ; in the female it is placed 

 near the anus. The Linguatulidce lay eggs, and from each egg, after 

 being conveyed into an intermediate host, a four-legged larva, with rudi- 

 mentary mouth parts, hatches out. It goes through a series of meta- 

 morphoses, and passes through a second larval condition, which, however, 

 possesses the essential characteristics of the fully developed form. Sooner 

 or later it migrates during this stage, and reaches its final host, mammal or 

 reptile, in the nostrils or lungs of which the adult Linguatulidce live. 



Linguatula rhinaria (Pilger), 1802. 



Syn. : Tcenia rhinaria, Pilger, 1802 ; Polystoma tcenioides, Rud., 1810 ; 

 Linguatula tcenioides, Lam., 1816. Pentastoma tcenioides, Rud., 1819. 



The male is white in colour, 1820 mm. in length, anterior 

 portion 3 4 mm. in breadth, posterior part 0-5 mm. in breadth. 

 The female is of a yellowish colour, 8, 10, or 13 cm. long, anterior 

 part 8io mm. and posterior part 2 mm. wide. The brownish 

 eggs can be seen in the median line. The body is elongated, 

 rather flat, and exhibits about ninety rings or segments and 

 crenellated borders. The hooks round the mouth are strongly 

 curved and are articulated to a basilar support. Eggs oval, 0-09 in 

 length, 0-07 in breadth. 



Linguatula rhinaria, in the adult condition, lives in the nasal 

 cavity and frontal sinus of the dog, wolf, fox, horse, goat, and 

 occasionally of man ; it causes severe catarrh, epistaxis and 

 suppuration. 



1 What are designated as stigmata in the Linguatulides are the orifices of seba- 

 ceous glands. 



