of the Fishery Board for Scotland. 



303 



Plaice. — These eggs appear as a rule in the Bay about the beginning of 

 March, in the surface and mid-water nets, and have a diameter of *068 in., 

 but they are comparatively few in number during this month. They are 

 more abundant about the end of April. None were observed after the 4th 

 of May. They have also been procured from the Moray Firth on the 20th 

 April. The announcement that Mr Scott found ova of the plaice abundant 

 in the Moray Firth in January shows that considerable latitude must be 

 given to marine fishes in regard to the period of spawning, a feature formerly 

 insisted on; indeed, a glance at the sizes of the various young forms at 

 any given time demonstrates the same fact, though here irregularity of growth 

 has also to be taken into account. The fact that so few ova of plaie • 

 occur in the Bay is in contrast with the condition on Smith Bank and othe^ 

 grounds and would corroborate the view already expressed that most of the 

 large (spawning) plaice are beyond the limit. 



The great size of the ovaries in a ripe plaice is noteworthy, and also the 

 comparatively large proportion of the ova which become ripe at a given 

 time. In one adult female,* 23 inches in length, each ovary measured 11 

 inches, and it was calculated that the ripe eggs amounted in bulk to about 

 a third or a fourth of the total bulk of the ovaries. 



The larval plaice is distinguished by its size, by the great breadth of the 

 marginal fin, and the canary-yellow colour, which is well marked posteriorly. 

 Mr Cunningham describes the yellowish pigment as in three rows on the 

 lateral region, but, as already mentioned, this has not been observed at 

 St Andrews. A peculiar feature is the presence of minute dark pigment- 

 specks on the ventral lobe of the marginal fin, whereas only one or two of 

 the yellowish corpuscles pass into the dorsal lobe from the tissue of the 

 body. The larva swims actively near the surface of the water, and is not 

 readily observed except by its large iridescent eyes, which now and then have 

 a golden sheen. Like other Pleuronectids it hangs head downward in the 

 water, and frequently bores its snout into the sand at the bottom. It 

 appears to grow rapidly, as forms, apparently referable to this species, 

 12 mm. long, are met with in April. 



What appears to be a larger egg of the same species occurs early in 

 March off the Tents' Moor and elsewhere in the Bay. It measures 

 •073 in. in diameter. This egg was found at various times up to the 4th of 

 May, the maximum period being about the 30th of April. In the majority 

 of cases (8) it was captured by the mid-water-net, but twice appeared in 

 the surface one. Each was characterised by a pale oleaginous area of 

 comparatively limited size lying under the lateral expansion of the 

 embryo at the upper arch of the egg. This area differs from an oil-globule 

 in its optical properties, and probably represents an oleaginous region 

 differentiated from the other parts of the yolk. The embryo was far 

 advanced, with the heart in active pulsation. The pigment was well 

 developed, chiefly chrome-yellow and black, especially the former. The 

 eyes were iridescent silvery. The capsule (zona radiata) is mostly dotted, 

 as in other forms, with a close series of rows of punctures. 



The embryo is comparatively large, with a series of dull yellow pigment- 

 grains from the front to the base of the tail, that is, they do not reach the 

 latter. The eyes are still iridescent silvery. The mouth is widely open, 

 and on the second day movements of the mandible were evident. The 

 dorsal marginal fin comes off from the top of the head. The surface of 

 the yolk is marked with stellate black chromatophores, and its anterior 

 part is rapidly absorbed; moreover, a few processes projected from the 

 posterior region forward into the anterior space. Some of the black 



* Kindly sent from the Moray Firth by Capt. Burn and Skipper Girdlestone. 



