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Part III.— Seventh Annual Report 



time, apparently from i to J of the total bulk being translucent in some 

 examples. The enormous number of these large eggs thus sent into 

 the water from a shoal of ripe plaice within a limited period must make 

 a noteworthy addition to the pelagic fauna. 



An egg with which I had long been familiar in March and April was 

 also found in the Bay this month, viz., a comparatively large egg measur- 

 ing '0675 inch, and having a capacious perivitelliue space, within which 

 is the isolated yolk measuring *041 inch. During the trawling expedi- 

 tions it was a common form at the surface on the rich grounds of! the 

 Forth. Mr Cunningham, too, found it in the same region a year later, 

 and figures it in his paper.* It is also frequently brought to the 

 laboratory from the Bell Bock grounds by the fishermen of St Andrews, f 

 Mr Cunningham, unfortunately, could not hatch the egg. At St 

 Andrews the early embryo lies on the yolk in the midst of the large 

 peri vitelline space (Plate III. fig. 1); but by-and-by the tail elongates, 

 the yolk becomes somewhat smaller, and the embryo stretches across the 

 entire area (Plate III. fig. 2), as well as tends to the upper arch in 

 floating. Before hatching, minute yellowish chromatophores are dotted 

 along each side of the embryo. When extruded the yolk-sac is large, 

 and the tail long. The embryo (Plate III. fig. 3) floats helplessly with 

 its large yolk-sac uppermost, though it twists and wriggles with great 

 vigour at intervals. The head is slightly yellowish by transmitted light, 

 and the round chromatophores along the sides have a deeper yellowish 

 tint. They extend nearly to the tip of the notochord. A tinge of the 

 same hue also occurs in the eyes, which are otherwise devoid of pigment. 

 The heart is broadly tubular, and pulsates very feebly. The tail bends 

 dorsally (i.e., downwards) as the animal floats. The relationships of this 

 form are still obscure. 



The pelagic forms in the Bay also included a large egg (about ^ inch) 

 with a pale oil-globule, the relationships of which are also at present 

 uncertain. 



In contrast with the condition in the Bay, the use of the surface tow-net 

 by the fishing boat 'Bose,'J south-east of the Bell Rock, towards the end of 

 the month, gave a much greater number of pelagic ova. Thus there were 

 a considerable number of the eggs with the large perivitelline space, 

 the diameter of the egg being *063 and the yolk # 042 inches (see Plate 

 III, fig. 1); other eggs were "044 inch, and a third series, also with 

 perivitelline space, *0675 inch and the yolk *041 ; while the ova of 

 the haddock, cod, rockling, and others were plentiful. 



Amongst the larval fishes characteristic of the Bay during this month 

 were young plaice, which were both captured in the mid- water net 

 and hatched from ova obtained by the same means. A detailed descrip- 

 tion has long been prepared, § so that it need only be stated here that the 

 larval plaice about a day old measures 7 mm., if the ova have been 

 recently captured before hatching. This length is '"much greater than that 

 given by Mr Cunningham, || viz., 4*1 mm., but there is this important 

 difference that his ova were fertilised artificially, and removed from the 

 ovum when almost ready to hatch. The larval plaice is a large form, and 

 is easily seen in the vessels. Moreover, the yellow pigment of those 

 observed at St Andrews (for three or four seasons) was not in the form of 



* Trans. Roy. Soc. Edin., vol. xxxiii. pt. 1, p. 105, pi. vii. fig. 2. 



t Amongst these James Gourlay and A. H. Cunningham deserve special notice. 



J A. H. Cunningham, skipper. 



§ Researches on the Food-Fishes, M'Intosh and Prince (now being published by the 

 Royal Soc. Edin. ). 

 || Op. cit., p. 99. 



