REPTILIA. 



Vertebrate animals characterized by having the blood cold with oval 

 nucleated corpuscles; heart usually with three chambers; circulation 

 incomplete; venous and arterial blood intermingled ; aortic arches two, 

 which coalesce or anastomose in front of the dorsal vertebrje ; reproduc- 

 tion oviparous or ovoviviparous ; embryo with amnion and allantois ; 

 respiration pulmonary in young and adult ; lungs with few cells ; met- 

 amorphoses none; occipital condyles one; rami of the lower jaw in 

 several pieces; os quaflratum present; nervous system cere bro- spinal ; 

 brain small ; lateral lobes of cerebellum, corpus callosum, and pons 

 varolii wanting ; corpora bigemina upon the upper surface of the brain ; 

 epidermal covering in the form of scales or plates. Excrementitious and 

 reproductive organs opening into a cloaca. 



Exclusive of the extinct 6rders, the following synopsis will refer an 

 animal to its proper place : 



Key to thb Orders of Ekphlbs. 



Epidermal covering in the form of plates, not united with the skeleton ; anal slit 

 longitudinal ; teeth conical, in sockets Crocodilia. 



Epidermal covering united with the skeleton forming a carapax and plastron ; teeth 

 none. ........ Tbstudinata. 



Epidermal covering in Che form of scales, rarely plates, distinct from the skeleton ; 

 anal slit transverse ; teeth conical, a. 



a. Eyelids usually present; month not dilatable; body usually lacertiloid 

 with four well developed feet Lacertilia. 



a. Eyelids none; mouth very dilatable ; body always serpentifarm, without 

 feet ; abdomen usually covered with large, entire, transverse scutellas. 



Ophidia. 



CROCODILIA, (Extralimital.) 



Body lacertiloid, of large size ; dermal armor composed of scutes and overlapping 

 scales ; anal slit longitudinal ; limbs four, well developed, anterior pair shorter, posterior 

 feet more or less palmate ; fingers five, toes four ; nails on the three preaxial digits 

 usually present ; eyelids three, distinct ; auditory openings with valves ; external nares 

 capable of closure ; teeth in a single row, in sockets ; tongue thick, fleshy, adherent its 

 entire length, and not protrnsible ; heart qnadrilocular, but with the pulmonary artery 

 and aorta connecting ; quadrate bone large ; palatines excluding the vomer from the 



