56 PRIMITIVE TREPHINING IN PERU [ETH. ANN. 16 
incision developed into curvilinear cutting, as in crania 9, 11, 12, 13, 
and 18 (the two earlier operations). In only one case (craninm 8) does 
the curvilinear cutting closely approach circularity, and even in this 
case one side is a tangent exceeding half the diameter of the aperture, 
while there are indications that the final rasping was designed to 
remove projecting termini and scratches produced in the gradual 
diversion of an originally rectilinear cut. 
Accordingly the first type of manipulation may be traced from simple 
rectilinear incisions, either random or arranged quadrilaterally, through 
various combinations of straight and curved cuts up to approximate 
circularity; in which form, of course, the extent of the lesion and the 
vital force required for recovery and reparation are reduced to a mint- 
mun. It is not known that this sequence has either geographic or 
chronologic significance; the lowest types (crania 1 and 2) are both from 
Huarochiri, as is also the highest (cranium 8), and there is nothing save 
the differentiation in method to suggest difference in period. It is on 
the whole probable that the differences in refinement in manipulation 
merely represent varying degrees of skill on the part of essentially 
contemporary operators. 
The elevation of the button outlined and partially dissevered by the 
incisions is indicated clearly in one case, and with strong probability in 
at least six others, and is suggested in several additional cases. In 
cranium 4 one of the margins of the irregular aperture is crushed, 
splintered, and undercut in such manner as to record unmistakably the 
application of the elevator lever-fashion over this part as a fulerum; 
while the broken edges of the inner table and the margins of the aper 
ture generally were evidently produced by the forcible elevation and 
breaking outward of the button. In cranium 15 the splinters and frag- 
ments of the fractured bone were evidently removed, either entire or in 
pieces, so forcibly as to leave jagged edges, especially of the inner table, 
and carry one side of the aperture beyond the incision designed to define 
it. In cranium 7 (the later operation) the thick button was apparently 
forced outward by strong pressure exercised by means of an elevator 
inserted in the incision and used as a lever fulcrumed on the outer wall 
of bone, whereby one of the margins of the aperture was carried beyond 
the limiting incision in the inner table; the thin edge of the inner 
part of the bone about the latest aperture in craniym 18 tells a similar 
story, and suggests that the tables were separated before the button 
was finally removed; and equally decisive are the jagged edges of the 
inner table part of the way around the immense aperture in cranium 19. 
In crania 1, 2, 5, 12, and 17 also there are jagged margins, especially of 
the inner table, which could have been produced only by the forcible 
removal of the button through outward pressure applied by means of 
an elevator. As with incising, so also with elevating, there are several 
cases in which no evidence of the process remains; but (excluding the 
examples of rasping) these are cases in which the marks of instrumen- 
