A loop is that type of fingerprint pattern in which one or more of the ridges enter on either side of the impression, recurve, touch or pass an imaginary line drawn from the delta to the core, and terminate or tend to terminate on or toward the same side of the impression from whence such ridge or ridges entered.
Essentials of a loop
● A sufficient recurve.
● A delta.
● A ridge count across a looping ridge.
A sufficient recurve may be defined as that part of a recurving ridge between the shoulders of a loop. It must be free of any appendages abutting upon the outside of the recurve at a right angle.
Appendages—Some explanation is necessary of the importance attached to appendages. Much care must be exercised in interpreting appendages because they sometimes change the shape of the recurving ridge to which they are connected. For example, a loop with an appendage abutting upon its recurve between the shoulders and at right angles, as in illustration 56, will appear sometimes as in illustration 57 with the recurve totally destroyed. For further examples see figures [161 to 184].
[Figs. 56-57]
The same is true of a whorl recurve, as in figures 58 and 59.