Reproductive Organs of Sparus Centrodontus. 7 



wide vas deferens, which finds exit on the top of the urogenital papilla. 

 The opening of the vfts deferens is inunediately in front of that of the 

 urethra (iirth.), the two apertures being separated by a thin, soft 

 septum. On the anterior side the outer and inner skins of the 

 oviduct wall join together to close the lacunar space, whicli com- 

 municates round the neck of the oviduct. 



On the end of the urethra there is a bulbous gland-like swelling. 

 When the papilla (pap., Fig. 29) is examined from the outside, the 

 single crater in its tip is seen to be divided by a transverse septum. 

 The papilla is not large ; it is larger in the male than in the 

 female : sometimes it is inconspicuous. It is well supplied with 

 blood, and is formed of very fine spongy tissue. The sides of the 

 crater are sometimes soft and gauzy ; this condition makes it difficult 

 to separate the two small apertures. 



The oviduct (ovd., Figs. 29, 81) opens in front of the vas deferens, 

 between it and the anus. The aperture appears to be partly closed 

 sometimes by the cohesion of its soft lips. The urogenital papilla 

 and the anal and oviduct apertures are sunk in the cloacal slit. The 

 slit is longitudinal and it closes neatly. 



When the female sex predominated the ovary was large, and pink in 

 colour. The testis was small, in some cases so reduced as to be hardly 

 visible. The ova, when -Smm in diameter, were just visible to the 

 naked eye. When magnified they were opaque, and were enclosed in 

 a swollen follicle (Fig. 20j. Some eggs from another ovary 

 measuring -Smm in diameter were not quite opaque. The nucleus 

 (germinal vesicle) was visible, and it was pigmented. Eggs which 

 are storing up yolk have orange-coloured pigment in them. The 

 pigment is located in the nucleus as a rim of oily opaque corpuscles 

 Ijn., Fig. 44). The size of the germinal vesicle varies (cp. Fig. 51). 

 It is possible that it has the power of expanding and contracting. 

 The clear eggs measured -ISnnn. in diameter. A few specks of red 

 colouring matter were made out in some clear eggs of that size. 



The general arrangement of the organs in the abdominal cavity is 

 shown in Fig. 2. The ovary was large and orange-coloured. The 

 testis (T) was rendered visible by some brown mottling along its 

 extent. The colouring matter is in little traces as well as in com- 

 parativeh^ big patches. 



A fine yellow mottling is to be seen scattered through some of the 

 ovaries. The ovarian ridges on the oviduct region of the ovary are 

 covered with a delicate cubicle, which can be easily dissected off in a 

 piece. 



The mesentery (dm., Fig. 40) attaches the ovary to the swim-bladder. 

 The principal blood-vessel is situated on the side facing the other ovary. 



The ovaries unite posteriorly, and end shortly thereafter. The 

 longitudinal egg-ridges, seen in section, tend to radiate from the large 

 blood-vessels. On the ridges are developed blunt villiform processes 

 full of ova. A developing ovary, which had been a spent, is 

 shown in Fig. 40. The testis, which is a very narrow fold, is in some 

 parts flush with the skin of the ovary. It could be traced right up to 

 the anterior end of the organ. The oviduct region (ovd.) is well 

 marked. In some cases, however, the testis began some distance short 

 of the anterior end of the ovary (cp. Fig. 22). 



The testis is sometimes hardly visible ; that appears to be the case 

 especially in ovaries that have been ripe before. The testis in Figs. 



