Wyman on the Cancelli of Bones. 139 
of the cancelli have been demonstrated. "The" columnar 
arrangement of the bony fibres of the’ vertebra seems the 
. most common. Asa general rule, the strength of the’ bone 
seems to be obtained in other mammals at the expense of its 
lightness, by giving greater thickness and density to tlie outer 
shell, as well as by stouter cancelli with smaller àreoké. 'The 
peculiar structure of the neck of the thigh; and of the astraga- 
lus seems to exist in man alone. The only animals in which 
I have detected any approach to the structure of the neck of 
the thigh in man, is in the two species of anthropoid African 
apes, the Chimpanzee ( Troglodytes niger,) and the Engé-ena 
(T. gorilla,) the two species which stand at the head of the 
brute creation, and which of all brutes make the nearest 
approximation to the erect attitude. In these, slight traces of 
the truss-work described in man, exist, but in them as in other 
animals the shell of the neck is much stouter and thicker. 
The structures which have been described in this commu- 
nication are found mainly, if not solely, in the bones con- 
nected directly with locomotion. And as they exist in man 
alone, or certainly present in him the highest degree of per- 
fection, we cannot escape the conviction that they relate to 
the kind of locomotion which he alone of the whole animal 
series can be said to possess, namely, that of walking erect, and 
Which requires in the passive and resisting organs subservient 
to it, in order that it may be effected with ease and grace, a 
nice combination of lightness with strength in the materials. 
His attitude more than any other, in consequence of the 
pillars of support being arranged in vertical planes, requires 
the most effectual means for counteracting shocks; for in all 
other mammals the points of support are usually four, and at 
the same time the bones of the legs make angles more or less 
acute with each other, and therefore are in a condition to 
yield readily by flexion to any increased force ; and this is true 
of all birds and reptiles. In the elephant, the thigh bones are 
vertical, but they are nearly at right angles with the vertebral 
column, and the pillars of support are four instead of two. 
