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CHAPTER XIII. 

 STRONGYLID^E. 



Strongylidce. Armed or unarmed mouths, no pharyngeal 

 bulb. In the males the cloaca is terminal and surrounded 

 by a membranous expansion, strengthened in most in- 

 stances by chitinous thickenings copulatory bursa. 

 There are one or two spicules, when two they are equal. 

 Larvae frequently rhabditiform. 



The family includes a very large number of species, 

 many of which are parasitic. An intermediate host is not 

 required as the development of the larva from the egg 

 takes place in the earth or water, and the parasitic life is 

 resumed only when the larvae have developed to some 

 extent. The most important genera of the Strongylidas 

 parasitic in man are Eustrongylus, Strongylus, Ankylo- 

 stomuni, (Esophagostomum and Triodontophorus. 



Eustrongylus. Large worms found in the pelvis of the 

 kidney, and sometimes in the abdominal cavities, of 

 various animals. In the male the copulatory bursa com- 

 pletely surrounds the cloaca as a collar-like process with 

 thickened edge but without strengthening ribs in which 

 are papillae. There is only one spicule. In the female 

 there is a single ovary, and the opening of the vagina is 

 in the anterior half of the body. 



One species, Eustrongylus gigas, a parasite of dogs, seals, 

 &c., has been described as occurring in man. The male 

 is 40 mm. in length, and the female up to 70 mm. The 

 spicule of the male is 5 to 6 mm. long. 



The eggs are oval and at the poles clear and colourless, 

 but elsewhere brown and thick-shelled, presenting numer- 

 ous depressions. They measure 0*064 by 0*05 mm. An 

 embryo slowly develops if the eggs be kept in moist earth 

 for months, but the further life-history is not known. 



