32 PRIMITIVE TREPHINING IN PERU [ETH. ANN. 16 
artificial aperture. The bone is somewhat bleached and cracked, but 
is in sufficiently good condition to indicate clearly the modus operandi. 
The locus of the operation is near the posterior angle of the bone, 
centering about 40 mm. to the right of the sagittal suture, and the 
same distance above the lambdoid. The aperture is elliptical, measur- 
ing about 22 by 45 mm. on the outer surface, somewhat less on the 
inner. Evidently it was performed chiefly by means of a single curvi- 
linear incision, apparently followed by the use of an elevator; and the 
scratches leaving the upper incision show that the curvilinear character 
was given by gradually changing the direction of the reciprocal or saw- 
ing motion as the incision was extended from the anterior extremity 
inward and backward. The marks indicate, too, that the instrument 
was a somewhat blunt single-point blade, which ground the bony sub- 
stance with rough sides as wellas a jagged tip. The sharp edges of the 
bone were not reduced after the operation, nor is there any sign of 
subsequent physiologic process. 
In this, as in some other cases, there is no certain means of determin- 
ing whether the operation was ante-mortem or post-mortem, though it 
must have dated about the time of death; but in this instance there is 
fairly decisive evidence that the operation was located by an antecedent 
lesion. Seven or 8 mm. outside the posterior extremity of the aperture 
there is a curvilinear crack in the outer table of the skull which, though 
partially obliterated by exploratory scratches, can easily be traced to 
its passage into the lower side of the aperture, where it invades the 
inner table and coincides with the margin of the opening thence nearly 
toits anterior extremity. While it would seem barely possible that this 
fracture might have been produced in connection with the operation, 
the indications are much stronger (amounting almost to conclusive evi- 
dence) that it antedated the operation, and was part of a depressed 
fracture, in which the bone was broken through in undercut fashion 
on the lower side of the aperture, and bent inward above, where the 
incision was afterward placed. 
lod 
CRANIUM 7 
(Plates XIII-XV) 
This specimen is fairly preserved, having been taken from a mummi- 
fied body, though it is weathered about the lower part of the left side, 
and somewhat about the occiput; no tissue remains, but portions of 
the bone are fatty and gelatinous. The skull is quite thick and strong, 
with an immense occipital protuberance; it measures 6 to 8 mm. in 
thickness about the loci of the two operations. The temporo-parietal 
sutures were incipiently anchylosed, as was also the coronal, especially 
on the right, though the sagittal and lambdoid remain conspicuous, 
the condition on the whole indicating full maturity. There are two or 
three irregular interparietals; while the metopic suture is distinctly 
preserved, 
