order to subdivide the 32 over 32 primary still further, the ridge
count of the whorl of the right little finger is used to obtain a
final classification. The extension above the normal classification
formula indicates that each whorl is classified as to the type;
namely, plain whorl (W), double loop (D), central pocket loop (C), and
accidental (X). Accordingly, it is not enough for the FBI
Identification Division to ascertain the general whorl pattern type,
but the deltas and core must show in order to obtain the ridge
tracing, the type of whorl, and also, in some instances, the ridge
count. The complete WCDX extension is outlined in Chapter VI.

Figures 366 to 377 are some examples of improperly and properly taken
inked fingerprints.

An examination of figure 372 shows that it is a whorl. In order to
classify the ridge tracing accurately, however, so that the
fingerprint card can be placed in the correct classification, the left
delta must show. The approximate ridge tracing for the whorl in figure
372 would be MEETING. An examination of the properly taken fingerprint
in figure 373 indicates that the correct ridge tracing is INNER. It
follows that the pattern in figure 372 would not have been placed in
the proper place in file.

[Illustration: 366. Improper.]

[Illustration: 367. Proper.]

[Illustration: 368. Improper.]

[Illustration: 369. Proper.]

[Illustration: 370. Improper.]

[Illustration: 371. Proper.]

[Illustration: 372. Improper.]

[Illustration: 373. Proper.]

The correct whorl tracing is needed to obtain the complete
subsecondary and the major classifications.

It may be noted that both deltas are present in figure 374. This would
enable the technical expert to ascertain the correct ridge tracing,
OUTER. In the core of the whorl, however, there is a heavy amount of
ink which makes it impossible to determine the type of whorl with any
degree of accuracy. If one were to hazard a guess, it would appear to
be a plain whorl. Actually, the correct type of whorl, a double loop,
is clearly visible in figure 375.

It can be ascertained that the pattern in figure 376 is a loop, but an
accurate ridge count cannot be obtained because the left delta does
not appear. The approximate ridge count of this loop is 14 to 16.
This approximation is sufficient for a fingerprint expert to place
this loop in the "O" group of any finger of the subsecondary. The
correct ridge count of this loop is 19, and it appe