Leptotyphlopidae:

Slender Blind Snakes are relatively small snakes that rarely exceed 30 cm in length ( Leptotyphlops macrolepis and L. occidentalis being the exceptions). The cranium and upper jaws (maxillae, palatines, and pterygoids) of leptotyphlopids are immobile and teeth are present only on the dentary bone. The lower jaw consists of an enormous, horizontally displaced qudrate, a tiny compund bone, and relatively larger dentary, angular, splenial, and coronoid (Pough et al. 1997).