26 PRIMITIVE TREPHINING IN PERU [BTH. ANN. 16 
CRANIUM 1 
(Plates I, IT) 
Ixcepting a spot on theright side, whichis somewhat weathered and 
eroded through exposure, this skull is firm, strong, and exceedingly 
well preserved. It was taken from a semimummified body, and shreds 
of tissue remain attached. It displays a single operation, so far com- 
pleted as to reveal the methods pursued by the primitive practitioner 
with remarkable clearness, together with an incomplete supplementary 
incision. The thickness of bone, measured on the incisions, is 6 to 
Tmm. The condition of sutures and teeth indicates mature but not 
advanced age. 
The operation was located near the crown, i. e., in the upper and for- 
ward part of the left parietal, involving the sagittal suture and ap- 
proaching the frontal. The aperture is an approximate parallelogram, 
averaging 17 by 22 mm., measured on the outer surface, and about 25 
min. less, in either dimension, measured on the inner surface. As 
clearly shown by the projecting extremities, the rectangular button was 
dissevered by means of two pairs of approximately parallel incisions, 
crossing approximately at right angles. Allof the incisions were more 
extended than the apertune, ranging from 42 to 50mm. in Jength: The 
incisions are V-shape in cross-section; none end abruptly, but simply 
narrow and shallow to the points of termination. The two more nearly 
longitudinal incisions are sharply defined quite to the termini, though 
there is a minor cut nearly parallel to the medial cut (Shown in plate 1), 
indicating a change in position and direction of the incision early in 
the operation. The lateral extremities of the transverse incisions are 
somewhat indefinite, showing a number of scratches and cuts produced 
by slips or clumsy manipulation of the instrument. (These marks are 
imperfectly reproduced in the plates.) All four of the principal inci- 
sions penetrated both tables of the skull fora part of their length, both 
the transverse cuts (especially the posterior one) passing beyond the 
medial longitudinal incision in such manner as to show that the intra- 
cranial tissues must have been injured by the operation; while at the 
latero-posterior angle the rudely executed, incisions did not extend quite 
through the inner table, and a projecting edge of bone remains, sug- 
gesting that the button was removed by the use of an elevator inserted 
at the medio-anterior corner, 
There is no indication of effort to smooth the sharp edges left by the 
cutting, nor is there any indication of subsequent growth. Moreover, 
there is some discoloration of the bone about the incision, indicating 
incipient decomposition in advance of mummification. Accordingly it 
seems probable that the individual did not survive the operation—indeed 
the posterior transverse incision must have penetrated the meninges 
and invaded the cerebral tissue for a length of 12 mm. and a depth and 
width of 2 or 3 mm., and must have produced or hastened death. 
