75 



b. Body shorter, but sometimes considerably elongated ; limbs 

 present or absent ; bones of upper jaw firmly connected with 

 remainder of the skull; mmi of lower jaw connected by 

 suture. I/izards. Lacertilia, p. 131. 



B. Body more or less protected by an armor of articulating bony scutes ; 

 these usually overlaid by firm epidermal plates of similar or dif- 

 ferent shape ; absent, however, in some turtles. 



a. Body short and broad ; encased in a bony shell formed above of 



the expanded ribs, below of dermal bones ; four limbs ; jaws 

 covered by horny beaks ; no teeth. Tortoises. 



Ghelonia, p. 142. 



b. Body lizard -like ; more or less protected by transverse series of 



dermal bones; limbs four; jaws provided with teeth. Croc- 

 odiles and alligators. Extralimital. Crocodilian 



Order OPHIDIA. 



Snakes, 



Animals having a greatly elongated body and a tapering, pointed tail. 

 Limbs wholly wanting, except in the rare cases where hinder limbs are 

 believed to be represented by a pair of anal spurs. Vertebrre many and 

 strongly articulated. Ribs movable and employed in locomotion. Brain- 

 case consisting of a reduced number of bones, which are firmly con- 

 nected and form an efficient protection to the brain. Bones concerned in 

 the seizing and swallowing of the prey — the palato-pterygoids, maxillre, 

 the quadrate and the squamosal — are loosely connected with the cranium 

 and with one another. Mandibles loosely joined in front by elastic tis- 

 sues. Gape of mouth usually large. No eyelids. Skin of upper sur- 

 face provided with small, usually overlapping scales; belly with larger 

 transverse scutes. Head usually covered with a few large, regularly 

 arranged plates. Vent a transverse slit. 



The Ophidia form a large and important order of Reptiles. They 

 inhabit all the great faunal regions of the globe. They are few in species 

 in the colder portions of the globe, but swarm in the hotter and moister 

 regions. They are divided by naturalists into a large number of fam- 

 ilies, but of these we have representatives of only the following three : 



