48 



Part III. — Twenty-eighth Annual Report 



The Ripe Eggs of the Halibut (Hippoglossus vulgaris), Flera. 



The ripe eggs of the Halibut have been obtained on two occasions from 

 the fish -curing yard of Mr. Angus, Aberdeen. 



Holt and M'Intosh have described the ripe eggs of this form, and little 

 remains to add to their descriptions. I have, however, made out what I 

 regard as a second investment to the egg. In addition to the zona which 

 is so prominently cross-hatched with short intersecting lines (z., fig. 8), there 

 is a delicate vitelline membrane closely investing the yolk. This was seen 

 crumpled in one of the eggs (vt., fig. 7). 



On 25th January a roe was obtained which had some clear eggs in it. 

 The fish had been caught by a trawler 145 miles E.N.E. of Aberdeen in 

 65 fms. Some of the ripe eggs were measured in sea water. They 

 varied from 2 75 to 3.2 mm. in diameter. Some of the ripe eggs were not 

 yet free from the follicle. Two of these measured 2 1 and 3 mm. re- 

 spectively. Some white opaque eggs measured 1'8 to 2 mm. in diameter. 

 This is probably the maximum size of the white yolked egg. 



A running halibut was observed by Mr. R. Thompson, at Aberdeen, on 

 March 1. It measured 175 cm. in length, and had been captured by a steam 

 liner on the West side of Scotland, viz., Flannan Islands, 12—13 miles 

 W. by N. i N. 



Another fish which measured 4 feet 3 inches (127 cm.) in length was 

 ripe on March 2. 



On May 2 a quantity of ripe ova was sent to the Laboratory in a small 

 box. The halibut from which the eggs had been taken was described after- 

 wards as being about 4 J feet (130 cm,) in length. It was believed to have 

 been caught on the Viking Bank, between Shetland and Norway. The eggs 

 formed a fluid mass, but they were quite free from one another. They 

 were quite translucent and showed no oil globule. They measured from 3 

 to 3*35 mm. in diameter. 



M'Intosh had examined the ripe eggs taken from a halibut caught about 

 150 miles E.N.E. from Peterhead in April. The present records extend the 

 spawning period for the northern part of the North Sea to five months, viz., 

 January to May. 



The Eggs of Conger vulgaris. 



All the specimens of this species here dealt with were kindly supplied by 

 Mr. Eunson, fish merchant, Aberdeen. 



Two Congers measuring 6 feet 1 inch (180 cm.) and 6 feet 3 inches 

 (185 cm.) were examined on 13th November, 1908. The ovaries were 

 very large, filling a large portion of the abdominal cavity in both. 

 Eggs were issuing in a small quantity from the genital aperture. That 

 circumstance was probably due to the rough treatment to which the 

 fishes had been exposed. The eggs were white, opaque, and measured 

 from *47 mm. to '65 mm. in diameter. An albuminous fluid exuded from 

 the aperture with the eggs. It coagulated in sea water, binding the eggs 

 together in a translucent matrix. In an hour or two afterwards the mucous 

 had dissolved, setting free the ova. The eggs showed only a trace of a 

 separation of the zona from the yolk. After preservation in formaline, 

 some of the eggs showed a fairly wide peri- vitelline space. 



In view of the fact that Cunningham* found that the ripening congers 

 were undergoing a process of degeneration, attention was paid to the bodily 

 structure. Both fishes were dark-coloured. One especially was black all 

 over except for the belly, which was a little lighter in colour than the rest 

 of the body. The second specimen had a dark-slate dorsum, with a light- 

 slate-coloured ventrum. 



* "Marketable Marine Fishes." London, 1896. 



