ENTOZOA. 



109 



sexes, it is commonly imbedded so tightly in a condensed portion of 

 the periphery of the lung, as to be with difficulty extracted ; the anal 

 extremity, on the contrary, hangs freely in the larger branches of 

 the bronchi, where the coitus, in consequence of the above disposition 

 of the female organs, may readily take place. 



In the Strongylus armatus, the two oviducts 

 terminate in a single dilated uterus, and the vulva 

 is situated at the anterior extremity of the body, 

 close to the mouth. 



I find a similar situation of the vulva in a species 

 of Filaria, about thirty inches in length, which 

 infests the abdominal cavity of the Rhea, or Ameri- 

 can ostrich. The single portion of the genital 

 tube continued from the vulva, is one inch and 

 a quarter in length ; it then divides, and the two 

 oviducts, after forming several interlaced convolu- 

 tions in the middle third of the body, separate ; 

 one extends to the anal, the other to the oral ex- 

 tremities of the body, where the capillary portions 

 of the oviducts respectively commence. 



In the Ascaris vermicularis^ the vulva i^fig- 

 47, e) is situated about one fourth of the length of 

 the body from the head. One division or horn 

 of the uterus, with its capillary ovarium, passes 

 towards the forepart of the body ; the other di- 

 vision towards the opposite end. 



In the Ascaris lumbricoides the female organs 

 {Jig. 46.) consist of a vulva, a vagina, and a uterus, 

 which divides into two long tortuous oviducts, 

 gradually diminishing to capillary tubes, which 

 form the ovaria. Both divisions extend back- 

 wards from the point of bifurcation. All these 

 parts are remarkable in the recent animal for 

 their extreme whiteness. The vulva is situated 

 on the ventral surface of the body, at the junction 

 of the anterior and middle thirds of the body, 

 which is generally marked at that part by a slight 

 constriction. The vagina is a slightly wavy canal 

 five or six lines in length, which passes beneath 

 the intestine, and dilates into the uterus. This 

 manifests strong peristaltic motions in the living 

 worm. The division of the uterus soon takes place, and the cornua 

 extend with an irregularly wavy course to near the posterior extremity 



d 



Ascaris vermicularis 

 (magnified). 



