REPTILIA. 



SYNOPSIS OF ORDERS. 



A. Cloacal aperture transverse; penis double; dorsal verte- 

 brfe movable upon one another and ribs upon them; teeth 

 present; lungs free; limbs when fully developed, with free 

 digits; heart trilocular. 



a. Rami of lower jaw loosely united in front by ligament 

 and muscle, attached behind to a movable quadrate 

 bone, which in turn is connected with a movable squa- 

 mosal ; palatine united to pterygoid only ; no pectoral 

 arch or urinary bladder; no eyelids or tympanic 

 cavity Ophidia. 



h. Kami of jaw more firmly ui^ited; no movable squamosal; 

 anterior ends of palatines united to maxillge and 

 vomers; pectoral arch and urinary bladder present; 

 usually with movable eyelids and a tympanic cavity. 



Lacertilia. 



B. Cloacal aperture round or longitudinal; penis simple. 



a. A dorsal shield or carapace present, composed of the 

 much-flattened spinous processes of the dorsal vertebrae, 

 and the greatly expanded ribs, which are united to 

 superficial bony plates ; ribs and dorsal vertebrae 

 immovable; all vertebrae without transverse processes; 

 an abdominal plate or plastron; pectoral and pelvic 

 arches within shield; scapula and precoracoid anchy- 

 losed ; quadrate firmly united to skull ; heart trilocular; 

 lungs fixed against inner periosteum of carapace; no 

 true teeth; urinary bladder present Testudinata. 



h. 1^0 carapace or plastron ; anterior dorsal vertebrae with 

 elongated and divided transverse processes; teeth in 

 sockets; lungs free; four well-developed limbs; heart 

 quadrilocular; rami of lower jaw united by suture; 

 quadrate immovably fixed to skull; no urinary bladder; 

 movable eyelids, and rudimentary external ear. 



(JroGodilia. 



