of the Fishery Board for Scotland. 



131 



as well as the changes in the germinal vesicle in more advanced eggs, is 

 more fully explained elsewhere (see p. 108). 



2. The John Dory {Zeus Faber). 



The eggs of this fish have not hitherto been described, but the spawn- 

 ing period is fairly well ascertained. Holt, during the scientific survey 

 of the fishing ground on the west coast of Ireland, found females ripe 

 in July and August, and one spent in June."^ Cunninghamt also found 

 ripe females in August, at Plymouth. The eggs, however, have not been 

 described. Cunningham suggests that they may be of the same type as 

 those of Capros aper, namely, buoyant and transparent ; but an examina- 

 tion of the ovarian eggs does not bear this out. 



I obtained the ovaries of a dory caught on 24th April, which weighed 

 about three pounds, the ovaries weighing just a little over three ounces. 

 Each ovary was flattened, broadly tongue-shaped, and attached to its 

 fellow by the inner margin or base by strong fibrous tissue — that is to say, 

 connate ; it measured eight centimetres in length, and the attached margin 

 was also eight centimetres long (fig. 8, PI. III.). The capsule was markedly 

 thick and tough. On cutting the ovary open, the lumen was found to be 

 relatively very large, and the ovigerous lamellae projected at most about 

 one centimetre into the sac. The ovarian stroma was abundant, dense, 

 and tough, and the largest growing eggs were about l'3mm. in diameter. 

 On carefully searching the lamellae I discovered a few large eggs, obvi- 

 ously a remnant from the preceding spawning period. The largest of 

 thesB was shrunken, the zona being wrinkled and crumpled, but by soak- 

 ing it in water it was made to assume more of its normal shape. It was 

 white and opaque-looking to reflected light, the zona showing distinct 

 appearance of concentric lamination. On putting on the cover-glass 

 its weight alone pressed out some of the yolk, and also globules of oil, 

 and the egg in this condition measured 2 '7 2mm. In optical section the 

 capsule showed three distinct layers, and was 0T5mm. thick. Under 

 a low power the surface of the capsule exhibited fine wrinklings, like 

 interwoven convolutions (Zeiss A., oc. 2), and very fine apparent stria- 

 tions. On applying pressure to the cover-glass more oily matter exuded, 

 and the capsule burst. The surface of the flattened membrane now 

 appeared minutely dotted, the dots being arranged, or catching the eye, 

 in linear order, and a high po^ver revealed a minutely honeycombed 

 appearance, without wrinkles.. The diameter of the flattened capsule 

 was 3*48mm. Another capsule found among the laminae measured 

 2'88mm. under the cover-glass, without any pressure but its weight. 



Eggs smaller in size, but still large for ovarian eggs, were found 

 imbedded in the stroma. One of these measured l'39mm., as taken 

 from the ovary; immersed in sea-water it measured l'52mm. It was 

 white by reflected light, and quite opaque, and was still contained 

 within the follicular investment, blood-vessels being visible on the 

 surface. On being isolated and placed under the cover-glass the contents 

 had a brownish appearance with transmitted light, and two separate 

 groups of oil-globules were faintly visible — one consisting of three and 

 the other of four larger globules, each being about 0'08mm., with 

 numerous smaller globules, about 0'018mm., around them. Some 

 other eggs, slightly smaller, contained a prominent oil-globule of a straw 

 colour; thus, in an egg of l*02mm. the globule measured 0*25mm. 



* Report of the Council, Royal Dublin Soc, p. 245. 1892. 



t"The Natural History of the Marketable Marine Fishes of the British Islands," 

 p. 322. 1896. 



