ust be located at the end
nearer the core. Ridge A in figure 30 is of this type.

In figure 31, A--A and B--B are the type lines, with the dot as the
delta. The bifurcations cannot be considered as they do not open
toward the core.

[Illustration: 31]

[Illustration: 32]

In figure 32, the dot cannot be the delta because line D cannot be
considered as a type line. It does not run parallel to type line A--A
at any point. The same reason prevents line E from being a type line.
The end of ridge E is the only possible delta as it is a point on the
ridge nearest to the center of divergence of the type lines. The other
type line is, of course, B--B.

The delta is the point from which to start in ridge counting. In the
loop type pattern the ridges intervening between the delta and the
core are counted. The core is the second of the two focal points.

_The core_, as the name implies, is the approximate center of the
finger impression. It will be necessary to concern ourselves with the
core of the loop type only. The following rules govern the selection
of the core of a loop:

- _The core is placed upon or within the innermost
sufficient recurve._

- _When the innermost sufficient recurve contains no ending
ridge or rod rising as high as the shoulders of the loop,
the core is placed on the shoulder of the loop farther from
the delta._

- _When the innermost sufficient recurve contains an uneven
number of rods rising as high as the shoulders, the core is
placed upon the end of the center rod whether it touches the
looping ridge or not._

- _When the innermost sufficient recurve contains an even
number of rods rising as high as the shoulders, the core is
placed upon the end of the farther one of the two center
rods, the two center rods being treated as though they were
connected by a recurving ridge._

_The shoulders of a loop are the points at which the recurving ridge
definitely turns inward or curves._

Figures 33 to 38 reflect the focal points of a series of loops. In
figure 39, there are two rods, but the rod marked "A" does not rise as
high as the shoulder line X, so the core is at B.

[Illustration: 33]

[Illustration: 34]

Figures 40 to 45 illustrate the rule that a recurve must have no
appendage abutting upon it at a right angle between the shoulders and
on the outside. If such an appendage is present between the shoulders
of