[Illustration: 246] [Illustration: 247] [Illustration: 248] Figures 245 to 254 have two deltas and one or more recurves, but they are classified as loops because each recurve is spoiled by an appendage connected to it at the point crossed by the line of flow. [Illustration: 249] [Illustration: 250] [Illustration: 251] [Illustration: 252] [Illustration: 253] [Illustration: 254] _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 ridge 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 another. 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. [Illustration: 255] [Illustration: 256] [Illustration: 257] [Illustration: 258] [Illustration: 259] [Illustration: 260] [Illustration: 261] [Illustration: 262] [Illustration: 263] [Illustration: 264] [Illustration: 265] [Illustration: 266] 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. [Illustration: 267] [Illustration: 268] _Accidental_ Within the whorl group the subdivision type "accidental" is used for extension purposes only. In general classification it is designated by the letter "W" and for extension purposes by the letter "X".