372 NOTES OxNT EXPERIMENTS RELATING TO THE 



was thirty-one. After the brill were separated from the flounders 

 they were fed with chopped worm^ which they ate very sparingly. 

 I was unable to get any other living fish which they seemed to 

 appreciate ; to small shore-fish such as gobies they paid no atten- 

 tion, I was afraid that they would not eat enough of the worm to 

 nourish themselves, but on my return to Plymouth after my holiday 

 I found that they were alive and had grown a great deal. They 

 still continue to live on worms, occasionally varied by Pecten and 

 pilchard, but they never feed eagerly and voraciously as the flounders 

 do. It is possible that in the natural condition young brill prey 

 upon smaller fishes, and that then they grow faster than my speci- 

 mens have on the diet supplied to them. But I could not afford to 

 feed them on living young flounders, and I shall have to find some 

 future opportunity of comparing the growth of the captive speci- 

 mens with that of free individuals. 



These young brill when brought to the Laboratory were 2*2 to 

 2"56 cm. {^ inch to 1 inch) in total length. They all possessed a large 

 air-bladder, and were able to sustain themselves for an indefinite 

 time at the surface or in mid-water ; but they frequently rested on 

 the sand at the bottom of the tank, and after a few days they swam 

 less and less above the bottom. Their metamorphosis was nearly 

 complete, but the eye of the lower side (the right) was either on the 

 edge of the head or only slightly within the edge on the upper side. 

 The dorsal fin did not extend forwards in front of the right eye as 

 it does in the adult, but only overlapped that eye for about one 

 third of its longitudinal diameter. The anterior dorsal fin-rays 

 were simple and undivided externally. Scales in the skin were not 

 visible externally. 



On August 28rd I took out one of these brill and preserved it in 

 spirit. It measured 6"65 cm. (2-| inches) in total length, 4*45 cm. 

 (If inches) in greatest breadth. It was in all respects closely similar 

 to the full-grown adult. The first five of the dorsal fin-rays were 

 divided into two branches at the ends ; and, in the first two, indi- 

 cations of further subdivision were visible. The dorsal fin extended 

 forwards in front of the transverse level of the right eye. The 

 circular scales were distinctly visible all over the upper (left) side by 

 the aid of a simple lens. 



Thus these brill have grown from about 1 inch to over 2| inches 

 in length in two and a half months. 



Five-bearded Rockling [Motella mustela, Linn.). — Several specimens 

 of the young of this species were brought to the Laboratory on 

 May 21st, having been caught in Sutton Pool along with the young 

 brill. When brought in they were about an inch long. One species 

 of Motella was spawning in our tanks in April of the present year. 



