No. 2.] THE SLOUDV OF VARTA TION. 471 
The small ossified scapulze are often very clearly shown on 
both the lateral and dorsal radiographs, and it is not a difficult 
matter to get an approximate idea of their relation to the neigh- 
boring vertebree. They ordinarily lie opposite the middle of the 
fourth vertebra, though they may lie opposite the intervertebral 
space which separates the third vertebra from the fourth, and 
less frequently opposite the space which separates the fourth 
from the fifth. They are represented on Plate C by the small 
cross-lines occurring between abscissas three and four. Let 
us examine the extreme cases, and see if there is a correlation 
between pelvic and pectoral variations. 
Specimens 12, 28, 30, 31, 35, 38, 39, 43, 52, 73*, 79%, 92, 
94* all show the scapulze to lie opposite or near the third inter- 
Wertebral space, while specimens 23, 24%, 37*,.53*5 58%,00™ 
71, 77, 78*, 83*, 89*, 90, 95*, 98 show a tendency towards the 
approach of the fourth intervertebral space. 
Now of the first series of thirteen specimens there are only 
three cases (indicated by an *) of forward homeceosis of the 
sacrum. In the second series, however, of fourteen specimens, 
there are nine cases of forward homceosis. 
When one stops to consider that the total number of homee- 
otic specimens is approximately only one-half the number of 
normal specimens, and that the chances of scapular variation 
are hence twice as liable to gather around normal individuals, 
the figures in the previous paragraph have an increased 
significance. 
We can conclude that variations in the relative position of 
the pectoral arch ave associated with variations in the relative 
position of the pelvic arch, and that both variations are causally 
connected with some common factor. I believe that factor to 
be the variation of the relative length of different vertebral 
regions, as considered in the fifth section. 
Section VII. 
Are there other skeletal variations associated with pelvic 
variation ? 
A critical examination of the skeletons of Necturus, made 
for the purpose of detecting a possible tendency on the part of 
