St. Andrews Marine Laboratory^ 51 



tiirbot at Dunbar degeneration had taken place to a consider- 

 able extent on the 7th September. In tlie centre of the 

 enlarged ovary was a space filled with glairy mucus, con- 

 taining degenerating ova which had formerly been fully 

 matured. The mucus was mixed with fatty debris and 

 granules, with shrunken egg-capsules. The fishes were 

 evidently getting rid of the eggs of the season, chiefly by 

 disintegration and absorption, while in the walls of the ovary 

 a crop of minute ova were developing in a healthy condition 

 and having a diameter of about '0762 millim. Between the 

 foregoing date and the beginning of April considerable change 

 had taken place in the ovaries ; thus, out of five examples 

 only one had many degenerating ova on the ovarian walls, 

 the capsules being wrinkled, collapsed, and opaque, while the 

 contents consisted of minute granules of yolk and oil-globules 

 which by transmitted light had a slightly yellowisli colour. 

 In the majority the capsule had ruptured and permitted the 

 contents to escape. The wall of the ovary itself consisted of 

 rugose laminee, chiefly longitudinal in the elongated posterior 

 region, or slightly oblique anteriorly where trending to the 

 oviduct. These lamina? were covered with developing ova, 

 the largest ranging from '2286 to 'oSlO millim., thus con- 

 siderably exceeding in size those of September. The ante- 

 rior region of the ovary appeared to be somewhat thicker than 

 the posterior and the ova slightly larger; but this may have 

 been accidental. The oviduct was occupied by a mass of 

 degenerating ova. Of the other four, three had a few degene- 

 rating ova between the folds of the ovaries and one had got 

 rid of the whole. All showed healthy developing eggs in the 

 ovaries, though the size was less than those of the first- 

 mentioned specimen. Under these artificial circumstances, 

 therefore, the retained ova are got rid of very slowly ; but such 

 a condition probably never takes place in the sea. It is, at 

 any rate, clear that the environment of the turbot at Dunbar 

 had been favourable for the development of the ovarian ova 

 and that, initial difficulties being overcome, it may yet be 

 possible to retain the spawning fishes from season to season. 

 When they become accustomed to confinement and find 

 themselves in favourable surroundings the " egg-bound " 

 condition, which is voluntary, may disappear. 



2. On the Ova and Larvce of Drepanopsetta platessoides. 



During the trawling expeditions of 1884 an e^g was fre- 

 quently found in spring, especially during March and April, 

 which was distinguished from all others by the large size of 



4^ 



