54 THE VOYAGE OF H.M.S. CHALLENGER. 



arc a series of quadrate genital masses (PI. VIII. fig. 10) along each side of the body 

 projecting into the peribranchial cavity. Each mass (PI. VIII. fig. 11) is composed 

 of a central testis, around which is the ovary. The testes are all connected by a con- 

 spicuous winding vas deferens, behind which is a wider oviduct. 



In Cynthia the testes and ovaria are usually united into one or more ramified or 

 lobed masses, which are placed between the inner surface of the mantle and the lining 

 membrane, which is pierced by the ducts opening into the peribranchial cavity. 



In Pelonaia there are two elongated genital masses, one upon each side and attached 

 to the mantle. Each consists of a tubular ovary, bent in a wide loop, with the oviduct 

 opening in front, and of a series of testicular vesicles arranged along the sides at right 

 angles to the ovary, and having ducts which pass across it to join a central vas deferens 

 terminating anteriorly along with the oviduct. 



In Stijela various arrangements are found ; — usually one or two long sausage dike 

 masses are formed, each of which is composed of a number of small ovaria and testes, 

 while in the nearly allied Polycarpa all the small glands are distinct, so that there are a 

 very large number of small ovaria and testes projecting from the inner surface of the 

 mantle, and each opening separately into the peribranchial cavity. In some species a 

 number of these small testes are arranged around each of the ovaries, and their ducts 

 join to form a common vas deferens opening beside the short oviduct. In several genera 

 of the Cynthiidse there are projections from the inner surface of the mantle, sometimes 

 pedunculated and rather like the genital glands, which have been described under the 

 name of " endocarps." They are formed chiefly of the connective tissue of the mantle, 

 and contain a large number of blood sinuses. Kupffer has noticed that they are 

 especially developed in species with a powerful musculature in the mantle, and hence he 

 considers that they are reservoirs into which the blood in the mantle sinuses may be 

 injected when the body is forcibly contracted. Possibly, as suggested by Hancock, they 

 serve merely as pads to keep the branchial sac and the genital glands apart. 



In Ascidia the ovary and testis are single racemose glands lying in the fold of the 

 intestine on the left side of the body (fig. 9, p. 40, and fig. 13, ov., p. 52), and some- 

 times extending partly over the wall of the intestine and stomach. The ovary is usually 

 a branched organ, the different branches uniting at a point near the centre of the 

 intestinal loop where the oviduct commences. This duct runs along the posterior border 

 of the intestine, and the dorsal edge of the rectum, to open into the peribranchial cavity 

 near the anus. The testis is formed of a large number of delicate white tubules which 

 branch dichotomously over the ovary, the stomach, and the intestine, and end in small 

 pyriform or elongated enlargements. A vas deferens, commencing like the oviduct at 

 the point of union of the tubules, runs alongside the oviduct during its entire course, and 

 terminates beside it in the peribranchial cavity. 



In Clavelina the genital glands he in the abdomen, on the left side of the intestine, 



