2616 THE REMAINING GROUPS OF REPTILES 



Many of these reptiles attained a length of from thirty to forty feet; and they 

 flourished throughout the whole of the Secondary period, that is to say, from the 

 epoch of the Trias or Red Sandstone to that of the Chalk, most or all of the forms 

 from the first-named deposits being of a more generalized type than those of later 

 date. 



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

 semblance 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 pre- 

 served 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 RHYNCHOCEPHAUA 



The tuatera, which seems to be confined to the small islands off the northeast 

 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 characterized 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 tem- 

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

 bones, which, generally at least, extend forward to meet the vomers, and thus 

 divide the palatines; while the anterior upper jawbones or premaxillae remain sepa- 

 rate from each other. The teeth are not implanted in distinct sockets, and are usu- 

 ally 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 vertebrae may be either hollowed at both articu- 

 lar 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 struc- 

 ture, but from their antiquity; representatives of the order occurring in the Permian 

 strata, immediately overlying the Carboniferous or coal-bearing rocks. While some 



