ROFL!
The basic constituents of the jaw are one fulcrum, and a pair each of unci, rami and manubria. There are several jaw types: malleate, incudate, virgate, uncinate, ramate and malleoramate. The type of jaw observed forms the basis for division into families.
Key:
F fulcrum; M manubrium; R ramus; U uncus.
The easiest jaw type to recognize, and shown here, is the malleate type, which is characteristic of the Brachionidae. All parts of the jaw are well developed and strong. The fulcrum is short and the rami broad. The unci have ridges across the surface terminating in teeth at the inner edge. The action of the jaw is to cut and chew, between the teeth, particles collected.