Plain ArchIn plain arches the ridges enter on one side of the impression and flow or tend to flow out the other side with a rise or wave in the center.
Tented ArchTented arches are similar to plain arches with the exception that the ridges in the center form a definite angle; or one or more ridges at the center form an upthrust; or they approach the loop type of pattern, possessing two of the basic characteristics of the loop, but lacking the third.
Ulnar LoopUlnar loops are those types of pattern in which the loops flow in the direction of the little fingers. The above pattern if on the right hand, and a radial pattern if on the left hand. The above pattern is also sometimes called a right slant loop, regardless of which hand it appears on.
Radial LoopRadial loops are those types of pattern in which the loops flow in the direction of the thumbs. The above pattern would be a radial pattern if on the right hand, and an ulnar pattern if on the left hand. The above pattern is also sometimes called a left slant loop, regardless of which hand it appears on.
Double Loop WhorlThe double loop whorl consists of two separate loop formations, with two separate and distinct sets of shoulders and two deltas.
Plain WhorlA plain whorl has two deltas and at least one ridge making a complete circuit, which may be spiral, oval or any variant of the circle. An imaginary line drawn between the two deltas must touch or cross at least one of the recurving ridges within the pattern area.
Central Pocket Loop WhorlThe central pocket loop whorl consists of one or more recurving ridges, or an obstruction at a right angle to the inner line of flow, with two deltas between which an imaginary line would cut or touch no recurving ridge within the pattern area,. The inner line of flow of a pocket loop whorl is determined by drawing an imaginary line between the inner delta and the center of the innermost recurve or looping ridge.
Accidental WhorlThe accidental whorl is a pattern with two or more deltas, and a combination of two or more different types of patterns exclusive of the plain arch. This classification also includes those exceedingly unusual patterns which may not be placed by definition into any other classes.