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Double Loop

Within the whorl group, the subclassification type double loop is

used for extension purposes only. In general classification it is

designated by the letter W.

The double loop consists of two separate loop formations, with two

separate and distinct sets of shoulders, and two deltas.

The word separate, as used here, does not mean unconnected. The two

loops may be connected by an appending rid
e provided that it does not

abut at right angles between the shoulders of the loop formation. The

appendage rule for the loop applies also to the double loop. An

appendage abutting upon a loop at right angles between the shoulders

is considered to spoil the loop, while an appendage which flows off

smoothly is considered to leave the recurve intact.

The fact that there must be two separate loop formations eliminates

from consideration as a double loop the S type core, the

interlocking type core, and the formation with one loop inside


The loops of a double loop do not have to conform to the requirements

of the loop. In other words, no ridge count is necessary.

It is not essential that both sides of a loop be of equal length, nor

that the two loops be of the same size. Neither is it material from

which side the loops enter.

The distinction between twinned loops and lateral pocket loops made by

Henry and adopted by other authors has been abandoned by the Federal

Bureau of Investigation because of the difficulty in locating and

tracing the loops. Both types have been consolidated under the

classification double loop.

Figures 255 to 266 are double loops.

Figure 267 is a plain whorl. It is not classified as a double loop as

one side of one loop forms the side of the other. Figure 268 is a

plain loop. It is not a double loop because all of the recurves of the

loop on the right are spoiled by appendages.