260 
ANIMALS IN MOTION. 
correspond with those of the alligator. The chameleon 
was carefully observed while walking on the ground, and 
while climbing the branch of a shrub. In both instances 
the movement of the limbs corresponded with the slow 
walk of an alligator. 
The walk of the Gallapagos turtle and of the common 
garden tortoise, disclosed the fact of their bodies being- 
supported on a pair of diagonals, alternately with three 
feet; the succession of foot-fallings conformed to the 
general law governing the same movement in other 
vertebrates. 
In the “ Naturalist in Australia,” Kent gives a most 
interesting description of the peculiar motions of the 
chlamydosaurus, or the frilled-lizard. The Roebuck Bay 
specimens brought to England by him— 
“ • . • were in vigorous health, and at the first trial when set at liberty, 
ran along almost perfectly erect with both their fore limbs and tail 
elevated clear of the ground. 
‘■The distance the chlamydosaurus will traverse in this remarkably 
erect position may average as much as 40 or 50 feet at a stretch; when, 
after resting momentarily on its haunches, it starts off again. When, 
however, a short stretch of a few yards only has to be covered, the 
animal runs on all fours. . . . Professor Huxley had no hesitation in 
assigning to this type an erect bipedal method of locomotion.’' 
The Flight and Soaring of Birds. The attention 
of the writer was first directed to the soaring of birds 
during a southern tour of the United States early in the 
fifties, when he watched a buzzard wheeling around, at 
various elevations, for the space of an hour, without the 
slightest apparent effort of motion. 
He once startled an eagle from a peak of the Sierra 
Nevada mountains; the bird gave two or three flaps of 
its wings, and without any further visible exertion, soared 
across the Yosemite Valley, and landed on another peak 
of the range, not less than three miles distant. The time 
was early in the morning, when there was not enough 
wind to extinguish a match struck in the open air ; yet 
the time in which the bird traversed this distance was not 
more than a few minutes. 
In “A Naturalist’s Voyage,” chap, ix., Darwin gives 
an interesting description of the soaring of the condor— 
“When the condors are wheeling in a flock round and round any 
spot, their flight is beautiful. Except when rising from the ground, I do 
not recollect ever having seen one of these birds flap its wings. Near 
Lima I watched several for nearly half-an-hour, without once taking off 
my eyes; they moved in large curves, sweeping in circles, descending 
and ascending without giving a single flap. As they glided close to my 
head I intently watched, from an oblique position, the outlines of the 
separate and great terminal feathers of each wing, and these separate 
feathers, if there had been the least vibratory movement, would have 
appeared as if blended together; but they were seen distinct against the 
blue sky. The head and neck were moved frequently, and apparently 
with force, and the extended wings seemed to form the fulcrum on which 
the movements of the neck, body, and tail acted. If the bird wished 
to descend, the wings were for a moment collapsed; and when again 
expanded with an altered inclination the momentum gained by the rapid 
descent seemed to urge the body upwards with the even and steady 
movement of a paper kite. In the case of any bird soaring, its motion 
must be sufficiently rapid, so that the action of the inclined surface of 
its body on the atmosphere may counterbalance its gravity. The force 
to keep up the momentum of a body moving in a horizontal plane in 
the air (in which there is so little friction) cannot be great, and this force 
