670 The Significance oj Human Anomalies. [November, 
this, with a band of ligament which connects its tip with 
the humerus lower down, forms a foramen or openingthrough 
which pass the great artery and nerve of the arm. This 
foramen is found in about 3 percent of recent skeletons, but 
much more commonly in the skeletons of ancient races. In 
very many bodies a trace of this foramen is seen, represented 
by a very small bony prominence, or only by a band of fibrous 
tissue. In many of the lower animals it is the normal con- 
dition. It is seen in nearly all the Carnivora, except the 
plantigrades (though it has been found in the cave bear) ; it 
is also seen in monkeys, lemurs, and sloths. In these it is 
generally completed by bone, though in some by bone and 
ligament, as in man. In the animals above mentioned it 
serves the purpose of protecting the great nerve and vessel 
of the fore-limb from pressure during flexion, and it also 
affords a more direCt course by which these structures can 
supply the parts below. In man when this arrangement 
occurs, owing to the altered position of the limb, the nerve 
and blood-vessel are actually dragged out of their course to 
pass through this opening ; so in him it serves no useful 
purpose. This variation is, as was first pointed out by Prof. 
Struthers, well known to affeCt certain families. The only 
reasonable explanation of the occurrence of this structure 
appears to be that of reversion to the type of some mamma- 
lian ancestor in which this part was functional, or, in other 
words, served a definite purpose (Struthers). 
Third Trochanter. — The third trochanter of the thigh-bone 
occurs about as frequently as the supra-condyloid process. 
On the upper part of the thigh-bone there are two promi- 
nences called the greater and less trochanter ; a third pro- 
minence ( trochanter tertius ) sometimes occurs ; it is situated 
a little below the great prominence, and gives attachment 
to the large muscle of the buttock ( glutceus maximus). Ac- 
cording to Fiirst, in forty skeletons of Swedes examined by 
him in the Caroline Institute in Stockholm, fifteen possessed 
this process, and in six skeletons of Laplanders four had a 
third trochanter. I have seen it in only about 1 per cent of 
the skeletons I have examined. In many of the lower ani- 
mals this process is enormously developed ; it is very pro- 
minent in the horse and rhinoceros, and in many others it 
exists in a slighter degree. 
One more example 1 from the osseous system and I shall 
pass to the softer structures. In the human wrist are eight 
small bones called carpals, and arranged in two rows; occa- 
sionally between the two rows we have a ninth bone called 
