THE BEAKED LIZARDS 



2617 



The Tuatera 



of these early forms appear to connect the order very closely with the Saurop- 

 terygians, others indicate an equally close relationship with the under-mentioned 

 Anomodonts. 



The single existing representative of the order (Sphenodon punc- 

 tatus) forms a family {SphenodontieUg) by itself, and likewise is the 

 representative of a distinct suborder (Rhynchocephalia Vera), characterized by each 

 segment of the shield on the lower surface of the body being formed of only three 

 elements, of which the middle one is chevron shaped, and likewise by the fifth met- 

 atarsal bone of the hind-foot being reduced in length and thickened in the same 

 manner as in lizards. The group is further characterized by the double nos- 



NEW ZEALAND TUATERA. 



(One-fourth natural size.) 



trils, the union of the two branches of the lower jaw by cartilage, and the deeply- 

 hollowed articular surfaces of the vertebrae. From its extinct allies the family is 

 distinguished by having a perforation on each side of the lower extremity of the 

 humerus or upper bone of the fore-limb; by the presence of hook-like processes to 

 the ribs, as well as of so-called intercentra, or additional segments between the 

 bodies of the vertebras; and likewise by the beak-like premaxillary bones carrying a 

 pair of somewhat chisel-like teeth, and the presence of only a .single row of teeth on the 

 palate, which are separated by a groove from the the row affixed to the edge of the 

 upper jaw. Into this groove is received the teeth and upper edge of the lower jaw, 

 which in very old individuals becomes as hard and polished as the teeth themselves, 



