SEA-FISHEEIES LABOEATORT. 69 



the top but stopped short 2 inches from the bottom of the' 

 tank. In the two compartments imperfectly separated by 

 this last partition, clean washed sand was placed so as to 

 reach to about 4 inches from the bottom. Consequently 

 all water escaping from the tank had to flow over the 

 first partition and under the second, filtering through the 

 bed of sand as it went. The object of this was to form 

 a sand trap which would let the water pass through, but 

 keep back the suspended fish eggs and embryos. By this 

 method the same water can be used to circulate through 

 several tanks containing different kinds of embryos. 



When on a dredging expedition on April 5th in the 

 steam-trawler " Rose-Ann " we brought up from the deep 

 channel, 12 miles S.W. of the Calf, bottom reamy mud, 

 depth 40 to 50 fathoms, a large number of spawning Hake, 

 Ling, Haddock, Plaice, and Witches. In fact nearly every 

 fish brought up from that spot was mature, and the 

 spawn was running out in quantities on the deck. When 

 I reported this to Mr. Dawson he arranged to bring the 

 "John Fell" over as soon as could be managed. She 

 arrived at Port Erin on Tuesday evening, April 21st, and 

 on Wednesday 22nd we were out trawling all day, on the 

 ground 12 miles S.W. of the Calf, and from there north- 

 wards towards Port Erin, with very poor results. We 

 boarded the steam-trawlers "Lady Loch " and " Oceanic " 

 which were working on the same ground, but got practically 

 no spawning fish in quantity. The only spawn we were 

 able to collect and fertilise was from some Witches 

 (Pleuronectes cynoglossus). This was taken to the labor- 

 atory and, as I considered it scarcely worth putting in one 

 of the hatching tanks, it was placed in an earthenware 

 vessel, where most of it afterwards hatched out. The 

 next day we again had practically no success ; and so, on 

 the following day, Friday, 24th, we tried further north, 



