16 



BATRACHIANS. 



of one of these measured as mucli as six feet in length. The size 

 of an ordinary Crocodile is from eight to nine feet, but they have 

 been seen twenty-four and even thirty feet long, with a mouth 

 opening from six to eight feet wide. 



In Ohelonians the surface of the skull is continuous without 

 movable articulations. The head is oval in the Land Tortoises, the 

 interval between the eyes large and convex, the opening of the 



Fig. 3.— Skeleton of a Tui-tle 



nostrils large, the orbits round. The general distinguishing 

 characteristic of Tortoises is the external position of the bones of 

 the thorax, at once enveloping with a cuirass or buckler the 

 muscular portion of the frame, and protecting the pelvis and 

 shoulder bones. The ribs are inserted by means of sutures into 

 these plates, and united with each other. A three-branched 

 shoulder and cylindrical shoulder-blade are characteristic of the 

 Tortoises. 



