APPENDIX B 631 



The Tetrapod Series 

 Four-legged "Land" Vertebrates 



Class 5. Amphibians. (Amphibia.) Primitive tetrapod vertebrates; eggs without 



a shell, embryo without amnion, larvae typically aquatic, respiring by gills; 



adults with highly glandular, usually scaleless skin, typically terrestrial and 



respiring by lungs; digits very rarely clawed. 



Subclass 1. Stegocephalians, Frogs, and Toads. (Apsidospondyli.) Includes the 

 *Labyrinthodontia, of which *Seymouria is one, and the modern frogs and 

 toads (Salientia or Anura). 



Subclass 2. Salamanders, Blindworms, and Their Kin. (Lepospondyli.) Includes 

 several extinct orders, the modern salamanders (Urodela) , and blindworms 

 (Apoda or Gymnophiona). 

 Class 6. Reptiles. (Reptilia.) Typically terrestrial tetrapods (some secondarily 



aquatic), respiring by lungs; with a shelled egg, dry cornified skin usually 



covered by scales or bony scutes, and toes usually clawed. 



Subclass 1. Cotylosaurs and Turtles. (Anapsida.) Includes the primitive 

 stem reptiles (*Cotylosauria) and the turtles and tortoises (Chelonia or 

 Testudinata). 



Subclass 2. Pelycosaurs and Mammal-like Reptiles. (*Synapsida.) Includes 

 the fin-backed reptiles (*Pelycosauria) and the mammal-like reptiles 

 (*Therapsida). 



Subclass 3. Ichthyosaurs. (*Parapsida or Ichthyopterygia.) Includes the 

 fish lizards (*Ichthyosauria). 



Subclass 4. Plesiosaurs and Their Kin. (*Euryapsida or Synaptosauria.) 

 Includes several groups of extinct aquatic reptiles, chief among which 

 are the plesiosaurs (*Plesiosauria). 



Subclass 5. Scaly Reptiles and Archosaurs. (Diapsida.) Includes two main 

 divisions: (1) the scaly reptiles (Lepidosauria), with the *eosuchians, 

 tuataras, lizards, and snakes; (2) the ruling reptiles or archosaurs (Archo- 

 sauria), with the *phytosaurs, crocodilians, *pterosaurs, and *saurischian 

 and *ornithischian dinosaurs. 

 Class 7. Birds. (Aves.) Body covered with feathers; forelimbs modified for 



flight; with a shelled egg, warm blood, and completely four-chambered heart. 



Subclass 1. Reptilian Birds. (Archaeornithes.) Includes *Archaeopteryx and 

 *Archaeornis (Jurassic.) 



Subclass 2. True Birds. (Neornithes.) Includes the toothed birds (*Odon- 

 tognathae, with *Hesperonis and *Ichthyornis) ; the ratite birds (Palaeog- 

 nathae, with ostriches, rheas, emus, casuaries, "elephant-birds" (*Aepy- 

 ornis), moas (*Dinornis), kiwis, and tinamous); and the carinate birds 

 (Neognathae, with loons, grebes, albatrosses and petrels, penguins, peli- 

 cans and allies, herons and allies, ducks and allies, hawks and allies, 

 pheasants and allies, marsh birds, *Diatryma, gulls and shore birds, doves 

 and pigeons, parrots, cuckoos and road runners, owls, goatsuckers and 

 whippoorwills, swifts and hummingbirds, African colies, trogons, king- 

 fishers and hornbihs and allies, woodpeckers and toucans, and perching or 



