70 
A TREATISE ON ELEPHANTS. 
become consolidated. The lateral surfaces present indentations for 
the reception of the cartilages of the sternal or true ribs. The 
sternum also helps to protect the heart and lungs from injury. 
Ribs. — The ribs constitute a series of long arched bones which 
are connected to the lateral sides of the spinal column above and 
mostly to the sternum below. There are from ig to 20 pairs, 
increasing in length from the first to the tenth, after which they 
decrease. They are divided into [a) true or sternal ribs, namely, 
those that join the sternum directly ; [b) false or asternal, those that 
do not ; and {c) floating ribs, those that have no attachment below. 
The first two or three sternal ribs are very stout and short, and only 
slightly curved, as the chest in this region is very narrow. The 
articulation between the heads of the ribs and the vertebrae in the 
region of the chest is a synovial one, permitting of a certain degree 
of motion. The ribs form the walls of the chest and protect the 
important organs within, their articulations with the vertebrae above 
and the breast bone below admitting of slight motion ; they assist 
in respiration. 
Pelvis. — Pelvis or haunch bone, so called from being likened to 
a basin, is the medium by which the hind limbs are connected to the 
body. It is of peculiar conformation, not unlike the human pelvis, 
and is set almost vertically to the spinal column. The acetabula are 
the cavities provided for the reception of the heads of the thigh 
bones, or femora. Owen states that ''the planes of the acetabula 
incline from the perpendicular about 70 degrees, a favourable position 
for transmitting w^eight upon the heads of the femora." There is no 
question that this construction is adapted for bearing downward 
pressure ; it is a conformation in w^hich immense strength is secured 
at the expense of suppleness, and is one reason why the gait of 
the elephant is such a source of discomfort to the rider. 
The extremities. — In the skeletons of most mammalia it will be 
observed that the bones of the limbs are set at certain angles in order 
to diminish shock, especially during such acts as leaping and 
galloping, w^iereas in the elephant the bones are not set at angles but 
almost in a vertical line ; the reason for this is apparent when we 
consider the immense size of the body to be supported. It is this 
particular formation that renders these animals incapable of making 
the slightest spring. Sanderson states that a trench 7 ft. wide 
is impassable to an elephant, though the step of a large one in 
full stride is about 6 J ft." From the position of the bones it is 
evident that the elephant is intended to sustain weight, i.e., is a beast 
of burden ; and this fact to some extent accounts for the discomfort 
experienced when riding these creatures. 
The fore-limb. — The clavicle or collar-bone is absent. 
