INVERTEBRATE ZOOLOGY. 51 



Sub-order 5. Anmdata. ... , . .No limbs or e3'elids — Epidermis divided 



into oblong fields by longitudinal and 

 transverse forms. -^ A mph isbaena . 



Order 2. Oi)hidia Body very much attenuated, limbs fail, 



no rudiment of shoulder girdle or ster- 

 num. A single lung developed (right). 

 Other paired organs placed the one be- 

 hind the other. -^ Crotalns, Python. 



[A single species of a very ancient type of lizard occurs in New Zealand, Sphenodon (Hat- 

 tena) punctata. The quadrate is immovable, ventral ribs and abdominal sternum are pres- 

 ent, the vertebrae are amphicoelous. It is referred to the Order Rhynchocephalia.] 



Sub-class II. Hydrosauria Cloacal opening oval in shape, its longer 



axis longitudinal. A single organ of cop- 

 ulation in the male, anterior to the cloaca. 

 Scales large and irregular, often rein- 

 forced by bony plates, which may 

 coalesce to form dorsal and ventral 

 shields. Mainly aquatic in habits. Quad- 

 ratum immovably attached to skull. 



Order 1. Chelonia Body enclosed by dorsal and ventral 



shields, formed partly bj' elements i^f the 

 endo-skeleton and partlj' from the integ- 

 ment. Teeth replaced by horny beak, 

 with sharp cutting edge. 

 ■^ Chrysemys, Chelone. 



Order 2. Crocodilia Body elongated, covered by large plates, 



which do not coalesce. Thoracic and ab- 

 dominal sterna present, connected by 

 ventral and dorsal ribs. Teeth large, in 

 alveoli, if Alligator. 



[Our knowledge of Reptilia is greatly increased by the discovery of several fossil classes 

 and orders. The Pterosauria were allied to the Lacertilia, and possessed membraneous ex- 

 pansions of the integument of the arms and fingers, by which they could fly. The Pleisio- 

 SAURiA and Ichthyosauria were hydrosaurs, the former somewhat resembling turtles, the 

 latter crocodiles. The Dinosauria included some enormous terrestrial forms with massive 

 skeletons, Brontosanrus, lynanodon. Other smaller Dinosaurs may have been the precursors 

 of birds. They walked mainly upon their hind feet, possessed pneumatic cavities in their 

 bones, and showed many other avian characteristics. An important form is Comp-wgnathus 

 (one specimen at Munich) which shows afhnity to Archaeopteryx (see introduction to Aves)]. 



