: ticular shape of the bone. 
1887] Variation of the Human Shoulder-Blade. ` 635 
tral surface downward, it will usually rest on three points,—the 
coracoid, and the superior and inferior angles. The vertebral 
border, as a rule, forms an arch, the highest point of which is 
sometimes about 2 cm. from the table. In other cases this border 
barely leaves the table, and sometimes one or both of the angles 
mentioned are bent dorsally, so as no longer to be points of 
support. 
On the dorsum the course of the spine and acromion deserve 
attention. By comparing the scapular and infra-spinous indices 
we get some idea of its obliquity. A high infra-spinous index 
with a moderate scapular index shows, of course, a greater 
obliquity, which is an ape-like peculiarity. When both are very 
high it shows simply a short, broad scapula. I called attention to 
the fact that one of the Kentucky mound-builders had a higher 
scapular index but a lower infra-spinous one than Broca’s negro, 
Tom Blaise, which means that the former had the relatively broader 
scapula, but the latter the more oblique spine. A study of the one 
hundred and thirteen Caucasian shoulder-blades shows that the 
two indices present no great discrepancies. The average scapular 
index being 63.50 and the infra-spinous 85.83, I find but three 
with a scapular index of between 64 and 65 which have an infra- _ 
spinous index below 85, and of these the lowest was 82.5. I find 
none at all with a scapular index above 65 and an infra-spinous 
below 85. Conversely, only seven having an infra-spinous index 
above 86 have a scapular index below 63. The lowest of these 
“S61 
Professor Mivart states that when the bone is so held that the 
long axis of the glenoid cavity is vertical, and that cavity is op- 
posite the eye of the observer, the acromion is almost always 
higher than the coracoid in man, troglodytes, and hylobates. I 
do not remember any exception to this rule in man, but I find a 
good deal of variation in the direction of the line formed by the 
projecting edge of the acromion when the bone is thus held. It 
is not easy to determine what angle it forms with the horizon, 
and I shall give the mean very vaguely, as probably in the neigh- 
- borhood of 45°, but I have seen it reach at least 65° on one 
hand and fall to 30° or less on the other. These two extremes 
are shown in Figs. 12 and 13. I have been unable to find that 
either of these degrees of inclination is assed with i! ee - 
