102 Prof. M'Intosh's Notes from the 



2. On the Ova and Larvce of certain Pleuronectids. 



The ova of most of the pleuronectids have been developed 

 at St. Andrews, but until recently those of the halibut and 

 long-rough dab have been enveloped in mystery. The large 

 eggs of the former, which Mr. Holt and I find to measure from 

 3"5 to 3'9 millim. or even more in diameter, have been pro- 

 cured by the former energetic observer at Grimsby, and about 

 the same time by Mr. Mackie, an officer of the Fishery Board 

 for Scotland, stationed at Peterhead — thanks to the exertions of 

 Dr. Fulton, the scientific secretary of the Board. Last year 

 again, Mr. Holt, when engaged off the west coast of Ireland, 

 proved that the egg with the large perivitelline space {egg of 

 Pleuronectid B)*, with which we had long been familiar, was 

 that of the long-rough dab. These ova were frequently 

 encountered in considerable numbers during the trawling- 

 expeditions of 1884, and Mr. Cunningham described and 

 figured the same form before hatching f. Further obser- 

 vations on the egg and the larva were given in the " Pelagic 

 Fauna of St. Andrews Bay " if, and in the " Researches " *, 

 where an account of the larval condition, with a coloured 

 figure by Prof. Prince, occurs. 



The ova of the pleuronectids group themselves in tliree 

 series, viz. : (1) those with a perfectly transparent yolk 

 devoid of oil-globules ; (2) those with a single oil-globule 

 which moves freely in the yolk ; (3) those with groups of 

 small or scattered larger oil-globules. In the first series are 

 the eggs of the halibut, long-rough dab, plaice, lemon-dab, 

 craig-fluke or witch {Pleuronectcs cynoglossus)^ dab, and 

 flounder. In the second group are the ova of the turbot, 

 brill, megrim, scald-fish, and topknot. In the third series 

 are the soles, the common species [Solea vidgaris) having a 

 ring of groups of minute oil-globules, and the others scattered 

 oil-globules of larger size. 



Though ripe eggs of the turbot were procured in the 

 trawling-expeditions of 1884, additional information has 

 since been obtained. The ripe unfertilized ova have a dia- 

 meter of from "99 to 1'06 millim. {Holt). Closely allied eggs, 

 which have a diameter of about •9906 millim., have been 

 captured in the tow-nets in summer for years, but their pre- 

 cise identification with those of the turbot has not been satis- 

 factorily made out by Mr. Holt or myself. The egg and larva 



* Trans. R. S. E. vol. xxxv. iii. p. 853, pi. x. fig. 8, and pi. xviii. 

 fig. 2. 



t Trans. R. S. E. vol. xxxiii. i. p. 105, pi. vii. fig. 2 (1887). 



\ 7th Ann. Rept. Scottisli Fishery Board, p. 270, pi. iii. figs. 1, 2, & 3. 



