74 LECTURE VI. 



drical tube or vagina, about an inch in length, is continued, which, 

 after forming a small convolution, terminates in the vulva, at the dis- 

 tance of two inches from the anterior extremity of the body. In 

 the Trichocephalus dispar the ovarium and uterus are continuations of 

 one and the same single tube, which by its folds more or less conceals 

 the intestines ; the vulva is situated nearly at the junction of the 

 filamentous with the thick part of the body. 



The theory which had suggested itself to Rudolphi of the correla- 

 tion of a simple oviduct in the female with the spiculum simplex of 

 the male, and of the double oviduct with a spiculum duplex, is dis- 

 proved by the circumstance of the uteri and oviducts being double in 

 the Strongylus armatus and in the Ascaris lumhricoides. In the 

 Strongylus injiexus, which infests the bronchial tubes and pulmonary 

 vessels of the porpesse, each of the two female tubular organs may be 

 divided into ovary, oviduct, and uterus ; the ovary is one inch in 

 length, commences by a point opposite the middle of the body, and, 

 after slightly enlarging, abruptly contracts into a capillary duct about 

 two lines in length, which may be termed the oviduct or Fallopian tube, 

 and this opens into a dilated moniliform uterus three inches in length. 

 Both tubes are remarkably short, presenting none of the convolutions 

 characteristic of the oviducts of Ascaris and Filarial but extend in a 

 straight line (with the exception of the short-twisted capillary com- 

 munication between the ovaria and uteri) to the vulva, which 

 forms a slight projection below the curved anal extremity of the 

 body. 



The reason of this situation of the vulva, seems to be the fixed 

 condition of the head of this species of Strongylus* In both 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 ex- 

 tremity, 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 Rheat 

 or American ostrich. The single portion of the genital tube con- 

 tinued from the vulva, is one inch and a quarter in length ; it then 

 divides, and the two oviducts, after forming several interlaced con- 

 volutions in the middle third of the body, separate ; one extends to 

 the anal, the other to the oral extremities of the body, where the 

 capillary portions of the oviducts respectively commence. 



