456 LOWER VERTEBRATES. 



sides of the body and liiding it, as it were, under the eaves of the shell. Chelys 

 matamata, the remarkable fimbriated or bearded-turtle, belongs to this family. This 

 is one of the most peculiar creations of nature, in oddity being exceeded by none. 

 It inhabits the warm fresh-water pools of the tropical portions of South America, and 

 has been, until of late years, quite abundantly found, tliough, from the unceasing draft 

 made upon it for food, it is now quite uncommon. It is said to be a carnivorous ani- 

 mal, lying in wait, concealed by the rushes of some quiet body of water, for an un- 

 suspecting fish or reptile, or possibly a brood of young ducks, which it captures by a 

 quick extension of its neck. It grows to a considerable size, sometimes reaching the 

 length of three feet. As is shown in the engraving, the snout is greatly prolonged, 

 and the sides of the head and ridges of the neck are provided with peculiar prolonga- 

 tions of the skin, the true office of which is not known. An allied form, Hydrastis 

 m(KcimiUanii, also inhabiting Brazil, has been given a family value by some naturalists. 

 The figure illustrating this animal shows the peculiar manner in which the head and 

 elongated neck is protected by being applied to the side of the body rather than being 

 withdrawn into the carajjax. 



The family Pblomedusid^ includes the single genus Pelomedusa, which is charac- 

 terized by having but two series of phalanges instead of the usual number, three. 

 P. suhrufa and other species inhabit South Africa. 



The highest family of the order, Steenoth^eid^, is based on the peculiar structure 

 of the anterior divisions of the plastron, which are separated transversely, giving the 

 animals ten plates instead of the usual number, eight. This peculiarity is similar to 

 that presented by the genus Pleurodira. 



Order V. — RHYNCOCEPHALIA. 



The fifth order of reptiles includes a small number of animals resejnbling in gen- 

 eral outline some of the lizards, though presenting several internal characteristics, as 

 the possession of bi-concave vertebrae and immo\able quadrate bones, which are at 

 variance with the forms already treated and are of ordinal value. But a single rep- 

 resentative, the Hatteria or Sphenodon of New Zealand, is still living, though the 

 paleontologist has brought to light the bones of a few pre-existing forms. 



The Hatteria is one of those isolated animals which, from the peculiarity of its 

 structure, is of interest to the anatomist ; as throwing light on the more obscure points 

 in the structure of fossil relatives, and, to the systematic zoologist, fills, as a single 

 specimen, the place of species, genus, family, and order. The general appearance is 

 iguana-like. The tail is compressed and crested, and, like many lizards, being of a 

 brittle nature, is often found reproduced, but without vertebral segmentation. The 

 general color is, above, dull olive-green spotted with yellow, and below, whitish. Be- 

 sides the peculiar fish-like vertebrae and rigid quadrate bones, some of the ribs are 

 provided medially with uncinate processes, resembling those of crocodiles, if not more 

 strongly those of birds. Third and intermediate portions, like those found in the 

 monotremes and sloths, unite the dorsal with the sternal costae. Teeth occur not only 

 on the jaws, but also on the palatine bones, where they ai-e arranged in a regular series, 

 parallel with those of the maxillaries. The total length seldom exceeds twenty 

 inches. At one time these animals were to be found in abundance along the rocky 

 shores and small islands of the New Zealand coast, where they lived in the crevices of 

 the rocks, or in small burrows of their own construction. Of late, however, being 



