[Fig. 309]
Figure 310 is a pattern which contains two elements of a loop but lacks the third. It is classified as a tented arch. Thus an impression having a delta and a recurve, but not having a ridge count across a looping ridge, falls into this classification.
[Fig. 310]
It will be noticed that although this pattern has the resemblance of a plain arch, the center of the impression actually contains a partially formed loop. A recurving ridge enters from the right side and exits in the same direction. A delta also appears just below the recurve. In attempting to obtain a ridge count, it is seen that the imaginary line drawn between the delta and the core runs directly along the ridge emanating from the former and which is joined onto the side of the recurving ridge. For this reason, no ridge count is possible.
Figure 311 is a tented arch. There are three loop formations, each one of which is spoiled by an appendage abutting upon its recurve between the shoulders at a right angle. It cannot be classified as an accidental as the patterns are all of the same type, i.e., tented arches. An accidental type of whorl is a combination of two or more different types of patterns exclusive of the plain arch.
[Fig. 311]
Figure 312 is a loop. It cannot be classified as a whorl of the double loop type because the formation above the lower loop is too pointed and it also has an appendage abutting upon it at a right angle.