'284 



NEMATHELMINTHES. 



Cloquet, the human round worm, 4 to 14 in. in length, a smaller variety in the 

 pig (A. suilla, Duj.). The eggs pass out into water or damp earth, and remain 

 there for some months, until the embryonic development is completed. They 

 are probably introduced direct into the alimentary canal of their host (Grassi 

 and Ebstein). The smallest worm found in the human intestine is 3 mm. 

 in length. A. megalocephala Cloq., horse and ox, may attain a length of 

 17 inches. A. mystax Zed., dog and cat, sometimes man. There is a large 

 number of species found in all classes of Vertebrates. 



Heterakis Duj. Polymyarian, hind end of male with a preanal sucker and 

 two lateral thickenings, spicules unequal, intestine of Vertebrates. 



Oxyuris Rud. Meromyarian ; pharyngeal bulb with teeth, hind end of female 

 thin and pointed, male with one spiculum, in Vertebrates and Insects (cockroach 

 and beetles) ; 0. vermicularis L., large intestine of man, introduced directly as 

 eggs- 0. curvula, caecum of horse; Nematoxys Sclm., in Amphibia; Oxysoma 

 Schn. ; Isakis Lespes, Arthropods and terrestrial Molluscs ; Labidurus Sclm. ; 

 Asiridocephalus'Dies.; Heterocheilus Dies.; Peritrachelius Dies. 



Fin. 232. Ascaris lumbricoides (after Leuckart). a, hind end of male with the two spicula ; 

 b, anterior end from the dorsal side, showing the dorsal lip with its two papillae ; c, the 

 same from the ventral side with the two lateral ventral lips and the excretory pore (P) ; 

 d, egg with the external membrane formed of small clear spherules. 



Fam. 2. Strongylidae. The male genital opening is at the posterior end of 

 the body, at the bottom of a bell-shaped bursa, the margin of which carries a 

 variable number of papillae; no pharyngeal bulb. Eustrongyhis Dies., poly- 

 myarian, with six oral papillae and a row of papillae on either lateral line. 

 The bursa is bell-shaped and completely closed, with regular muscular walls and 

 numerous marginal papillae. There is only one spiculum. The female genital 

 opening is far forward. The larvae live encysted in fishes (Filaria cystica 

 from Symbranchus). E. gigas Rud., the body of the female is three feet in 

 length, and only twelve mm. thick. It lives singly in the pelvis of the kidney 

 of the seal and otter, etc., and very rarely in man ; got by eating raw fish. 



Strongylus Rud. With six oral papillae and small mouth. Two conical 

 cervical papillae upon the lateral lines. The posterior end of the male has 

 an umbrella-like incompletely closed bursa. Two equal spicula, usually with 

 unpaired supporting organ. The female sexual opening is sometimes approached 

 to the posterior end of the body. They live for the most part in the lungs 

 and bronchial tubes. The larvae live in damp earth, and probably pass into 

 the host directly in the food. St. lonyevaginatus Dies. Body 26 mm. long, 

 5 to 7 mm. thick. The female sexual opening lies directly in front of the 

 anus, and leads into a simple ovarian tube. Only once found in the lung 

 of a six-year old boy, in Klausenburg. St. paradoxtis Mehlis, in the bronchial 



