252 BEAKED LIZARDS. 



Chalk, most or all of the forms from the first-named deposits being of a more 

 generalised type than those of later date. 



In external appearance the fish -lizards must have presented a marked 

 resemblance to whales, the place of which they seem to have filled in the old seas. 

 Like these animals, they were obliged to come periodically to the surface of the 

 water for the purpose of breathing; and they were likewise carnivorous, as is 

 attested not only by the conformation of their teeth, but likewise by the petrified 

 remains of their prey. Occasionally specimens are met with, in which entire 

 skeletons of one or more young individuals of the same species are preserved within 

 the cavity of the ribs, thus proving that in these reptiles the eggs were hatched 

 within the body of the females, and the offspring produced in a living condition. 



The Beaked Lizards. 



Order Rhynchocephalia. 



The tuatera, which seems to be confined to the small islands off the north-east 

 of New Zealand, is not only the most remarkable of all existing reptiles to which 

 the term lizard can be applied, but is the sole living representative of a distinct 

 family, as well as of an entire order ; and the difference between it and an ordinary 

 lizard immeasurably exceeds that by which the latter is separated from a serpent. 

 As an order, the beaked reptiles may be provisionally characterised as follows. 

 Externally most of these reptiles appear to have been more or less lizard-like ; 

 and, as in their living representative, the body was probably covered above with 

 small granular scales intermingled with tubercles. The skull differs essentially 

 from that of lizards in having the quadrate-bone immovably fixed by the upper 

 end to the adjacent bones ; and likewise by having both an upper and a lower 

 temporal arch. The hind portion of the palate is formed by the union of the 

 pterygoid bones, which, generally at least, extend forwards to meet the vomers, 

 and thus divide the palatines ; while the anterior upper jawbones, or pre- 

 maxillae, remain separate from each other. The teeth are not implanted in 

 distinct sockets, and are usually welded to the summits of the jaws. In the trunk 

 the ribs articulate to the vertebrae by single heads, and may have hook-like 

 processes similar to those of birds; while on the lower surface of the body 

 so-called abdominal ribs are always developed, forming a shield composed of a 

 number of segments, and comparable to the plastron of the tortoises. The 

 vertebras may be either hollowed at both articular ends, or the hinder surface 

 may be cupped and the front one ball-like. That the beaked reptiles form a very 

 primitive group is clear, not only from their structure, but from their antiquity ; 

 representatives of the order occurring in the Permian strata, immediately over- 

 lying the Carboniferous or coal-bearing rocks. While some of these early forms 

 appear to connect the order very closely with the Sauropterygians, others indicate 

 an equally close relationship with the under-mentioned Anomodonts. 



The single existing: representative of the order (Sphenodon 

 The Tuatera. ° . w 



punctatus) forms a family (Sphenodontidce) by itself, and likewise 



is the representative of a distinct suborder (Rhynchocephalia Vera), characterised 



