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THE DUCK-BILLS. 235 
they may be readily recognised by their dark bodies just seen 
level with the surface, above which the head is slightly raised, 
and by the circles made in the water around them by their 
paddling action. On seeing them, the spectator must remain 
perfectly stationary, as the slightest noise or movement will 
cause the timid creature instantly to disappear, so acute are 
they in sight or hearing, or perhaps in both; and they seldom 
reappear when once frightened. By remaining perfectly quiet, 
however, when the animal is paddling about, it is possible to 
obtain an excellent view of its movements in the water; it 
seldom remains longer than for one or two minutes playing on 
the surface, but dives, and reappears a short distance above or 
below the place at which it was observed to descend.” 
Later on, Dr. Bennett observes that ‘these creatures are 
seen in the Australian rivers at all seasons of the year, but are 
most abundant during the spring and summer months. . . 
The best time for seeing them is early in the morning or late 
in the evening. During floods and freshets they are frequently 
perceived travelling up and down the rivers; when going down, 
they appear to allow themselves to be carried by the force of 
the stream, without making any exertion; but in swimming 
against the current their muscular power is exerted to the ut- 
most to stem its force, and generally with success. I recollect, 
however, seeing two make repeated and ineffectual attempts to 
pass a small waterfall in a rapid part of the river, and, after 
many persevering efforts, they were unable to attain their 
object.” 
In describing the structure of the burrow, the same author 
states that on a certain occasion on arriving at the spot where 
one had been partially opened by the natives, he found it 
situated in a steep bank adjacent to the river, upon which 
grass and other herbaceous plants grew in abundance. The 
native guide, by whom he was accompanied, “‘ putting aside 
