OVARIES IN TELEOSTEAN AND ELASMOBRANOH FISHES. 163 



Teleostean fishes have, as a rule, a pair of ovaries, and the 

 single ovary of Zoarces h.as been shown by Jungersen 

 (1889) to be the outcome of the fusion of paired priniordia 

 in the embryo. The testes are also paired in the embryo, 

 and this condition is retained in the adult. Stuhlmann has 

 described the arrangement of the ova on the internal surface 

 of the ovarian wall. The eggs are not studded uniformly 

 over the entire inner surface, but are limited to certain 

 roughly longitudinal tracks, corresponding to low longi- 

 tudinal lamellae in the embryonic ovary. These lamellae, 

 which are conspicuous structures in many Teleostean ovaries, 

 arc suppressed in Zoarces^ and are not obvious in the adult 

 gland. The larger ova, however, instead of being sunk in 

 the substance of the ovarian wall, are singly contained in 

 vesicles or pouches which project from tlie wall of the ovary 

 into its cavity. Each ovigerous pouch is a simple outgrowth 

 of a portion of the wall, and its enlargement keeps pace with 

 the growth of the contained ovum. The pouches which 

 contain ripe or nearly ripe eggs are large pear-shaped 

 vesicles about 4 mm. long and about 3 mm. broad. On the 

 wide distal end of each is a cup-shaped depression, lined 

 with a peculiarly modified epithelium. The epithelium 

 consists of tailed cells, the tails resting on a basement 

 membrane. 



In the walls of each pouch is a network of blood-vessels. 

 The vascular supply of these structures and its development 

 have been described in detail by Stuhlmann (1887). It is 

 important to observe that these ovigerous pouches are 

 morphologically quite distinct from the ovigerous lamelhe 

 of other Teleosteans. 



Ovigerous la me lite are longitudinal or transverse folds 

 of the ovarian wall, and bear the germinal epithelium on 

 their free margins (pipe-fishes) and often on their faces. 

 Each lamella produces a great number of ova. In Zoarces, 

 however, the lamella) are suppressed, but each egg, as it 

 grows, becomes carried out on a separate papilla of the 

 ovarian wall. Not until the egg has attained a certain size 



