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the bucket, which was held in the water, and became attached 

 to the sides or to the glass front of the tank. The two largest 

 were, respectively, 7^ and 9 inches in length, coloured black 

 or dark grey dorsall3^ and lighter ventrally. The third 

 specimen was much smaller, being about 4 inches in length and 

 much lighter in colour. It was found attached to the roof of 

 the mouth, while the other two were attached externally to the 

 ventral surface of the shark. Their hold is very secure, and 

 they could not be pushed away without risk of injury. If, 

 however, the finger nail be inserted under the edge of the sucker, 

 they suddenly release their hold, and in an apparently indis- 

 criminate way at once attach themselves to the nearest object. 

 One of them happened to attach itself to the glass of the tank 

 so that its mouth projected above the surface of the water. It 

 remained in this position, though apparently in distress, until 

 it was forcibly removed. It was noted that they never, like 

 other fish when first put into the tank, unintentionally knocked 

 their heads against the transparent glass, but attached them- 

 selves to it at once. The turning movement, which is necessary 

 to attach the sucker, which is on the top of their head, to an 

 object in front of the fish, was performed so rapidly that the 

 details could not be followed by the eye of the observer. 



The other fish in the tank took very little notice of the 

 suckers, though they usually make a thorough inspection of 

 every stranger. One large Klip-fish, however, hovered around 

 one of the attached fish, and finally made a snap at its tail, 

 but immediately went off and paid no further attention to it. 



When first put into the tank, the sucker-fish remained in the 

 same position for about half an hour, when one went off and 

 attached itself to another part of the glass. Shortly afterwards 

 the largest left the glass, and swam about rather rapidly at the 

 surface of the water. Its method of swimming is worthy of 

 note. It progressed by a continuous undulating motion of 

 the whole body, occasionally making sudden darts as if at 

 objects on the surface of the water. During the whole time 

 it was swimming, the mouth was carried along the surface or 

 slightly under it, the posterior end of the body being rather 

 deeply submerged in the water. This position was maintained 

 by the use of the pectoral fins, which were constantly held in a 

 rigid position, and at such an angle as to raise the anterior part 

 of the body when in motion. The dorsal, anal and caudal fins 

 were used as organs of locomotion, undulating with the whole 

 body. The ventrals, however, were used in a totally different 

 way. When the fish moved forward they were closely 

 appressed to the body. Progress could however be quickly 

 arrested by the sudden erection of both of those fins, or a 



