EXCEETOEY AND EEPEODtTCTIVE SYSTEMS 235 



A. The Female. 



1. The ovary, which is single, is an elongated, soft, lobu- 



lated mass, varying a good deal in size, but usually 

 about two or three inches long in specimens of the 

 size described. It lies in the body-cavity a Httle to 

 the right of the median plane, and is attached to the 

 dorsal wall by a narrow fold of peritoneum, which is 

 very readily torn. 



The surface of the ovary is tuberculated, owing 

 to the contained ova. 



2. The oviducts, which are formed from the pronephric or 



Bfiillerian ducts of the embryo, are a pair of tubes 

 running along the dorsal wall of the body-cavity, 

 ventral to the kidneys, and not far from the median 

 plane. Their anterior ends curve inwards round the 

 sides of the oesophagus, and unite immediately behind 

 the pericardium, to open into the body-cavity by a 

 median ventral slit, through which the ova enter 

 the oviducts from the body-cavity. 



About a third of its length from the anterior end, 

 each oviduct expands to form the thick-walled ovi- 

 ducal gland, which secretes the horny capsules of the 

 eggs. Behind the glands the oviducts are large and 

 dilatable, and their posterior ends unite, and open by 

 a large median aperture into the dorsal wall of the 

 shallow cloaca, immediately behind the rectum. 



Find the anterior opening of the oviducts in the suspensory 

 ligament of the liver, immediately behind the pericardial 

 cavity : insert a seeker through it into the oviducts, and follow 

 one of these back to the cloaca, slitting open its ventral wall. 



3. The kidneys extend nearly the whole length of the body- 



cavity, lying dorsal to the peritoneum, and one at 

 each side of the vertebral column. The anterior 

 two-thirds of each kidney, or mesonephros, is rudi- 

 mentary, and appears as an ill-defined tract of soft 

 yellowish-brown degenerate gland-tissue. 



The posterior third, or metanephros, is a well- 



