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SUB-DIVISION AMNIOTA. 

 CLASS REPTILIA (REPTILES). 



Mention the general Features of Reptiles. Name the Orders 

 of Eeptilia, and give Examples. 



There is an exoskeleton of epidermal horny scales and 

 (frequently) dermal bony plates. The limbs, when present, 

 are pentadactyle. The bones are without epiphyses. The 

 skull has one occipital condyle ; and the lower jaw articu- 

 lates with the quadrate. The upper and lower jaws, and 

 (in certain forms) also the palatines and pterygoids, bear 

 teeth. The vertebral column has distinct cervical, thoracic, 

 sacral and caudal regions ; usually only two vertebrae form 

 the sacrum, and the caudal region (typically long) often 

 has chevron bones (haemal arches), generally attached 

 between the centra. Usually there is an ischial and a 

 pubic symphysis. The ankle joint is intertarsal. There are 

 twelve pairs of cranial nerves (except Snakes). There is 

 one ear ossicle, the columella. The gut and the urino-genital 

 ducts open into a cloaca. Respiration is by lungs. The 

 heart consists of a sinus venosus, two auricles and one 

 ventricle (two ventricles in Crocodilia) ; the conus is absent. 

 The ventral aorta is completely divided. The aortic arch is 

 paired in the adult. Most Reptiles are oviparous ; and the 

 eggs are large and have much yolk. The embryo has two 

 foetal membranes, the amnion (protective) and the allantois 

 (respiratory). 



The Orders of Reptiles are : 

 Order KHYNCHOCEPHALA. 



Example, Sphenodon, syn. Hatteria (the New Zealand 

 " lizard "). 



f Order LACEBTILIA (Lizards). Teeth fused, either to the ridges of the 

 jaws (acrodont) or to the sides of the jaw ridges (pleurodont). 

 Examples, Lacerta. 



Anguis (Slow-worm). Limbless, worm-like, 



burrowing, viviparous. 



Amphisbaena. Limbless, worm-like, burrowing. 

 Chamaeleon. 



Order OPHIDIA (Snakes or Serpents). Limbless. Teeth fused to the 

 bones bearing them. 



Examples, Typhlops. A burrowing snake. 



Python. A non-poisonous, crushing snake. 

 Vipera. Poisonous Maxillae are erectile, and 



each bears a modified tooth, the perforated 



fangs. 



