AMPHIBIA. 



28 7 



opus includes the burrowing spade 

 i except at the breeding-season. 

 arc Alytcs and Bombinator. The 

 HVLID.K have teeth, while the 

 tips of the toes are expanded into 

 sucking-disks. Our tree-toads be- 

 long to Hyla, Acris, and Choro- 

 philns ; NotodclpJiys and Nototrema, 

 tropital America. The extinct 

 PAL.KOBATRACHID/E (oligocene) 

 are noticeable for two sacral ver- 

 tebrae. 



ORDER III. FIRMISTERNIA. 



Tongue well developed ; epi- 

 coracoids firmly united in the 

 median line. The ENGYSTOMID^E, 



-foot toad which is rarely 

 Allied European genera 



FIG. 286. J S M Sternum and 

 ventral portion of f^-^r^\ the shoulder 

 girdle of Rana, \&%$j after Wieders- 

 heim, illustrating x ^ /x ^ tne firmister- 

 nous type of sternum, cl, clavicle ; co, cora- 

 coid ; ec, epicoracoid ; g, glenoid fossa ; os, 

 omosternum; s, ventral part of scapula; sf, 

 sternum; x, xiphisternum. 



FIG. 285. Shoulder girdle of 

 Bombinator igneus, showing the ar- 

 ciferous type, after Wiedersheim. 

 c, clavicle ; co, coracoid ; ec, epi- 

 coracoid ; g, glenoid fossa ; pc, pro- 

 coracoid ; j, scapula ; ss. supra- 

 scapula ; st, sternum. 



or toothless frogs, occur in 

 our southern states. Engy- 

 stoma. The RANID^:, or 

 true frogs, have smooth 

 skin, and teeth in the up- 

 per jaw. Rana contains 

 our species including the 

 bullfrog (R. catesbiana) 

 the largest known frog. 

 Rana first appears in the 

 miocene. Numerous other 

 families in the tropics, in- 

 cluding the DENDROBA- 

 TID^E, which have toes like 

 the tree-toads, Hylidae. 



SUB-CLASS IV. GYMNOPHIONA (C^ECILI/E). 



Limbless amphibia of worm-like shape ; tail lacking; vertebrae 

 amphiccelous ; skull well ossified, with well-developed ethmoid ; 

 body externally ringed, and bearing semi-circular dermal scales. 

 Frequently a protrusible tentacle in a tentacular sheath between 



