AMPHIBIA. 



287 



opus includes the burrowing spade- 

 seen except at the breeding-season, 

 are Alytes and Bombinator. The 

 HYLID.E have teeth, while the 

 tips of the toes are expanded into 

 sucking-disks. Our tree-toads be- 

 long to Hyla, Acris, and Choro- 

 philus ; Notodelpliys and Nototrema, 

 tropital America. The extinct 



PAL;OBATRACHID,E (oligOCCne) 



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. 

 ventral portion of 

 girdle of Rana, 

 heim, illustrating 



Sternum and 

 the shoulder 

 after Wieders- 

 t h e firmister- 



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 ; s, scapula ; ss, supra- 

 scapula ; st, sternum. 



or toothless frogs, occur in 

 our southern states. Engy- 

 stoma. The RANID.E, or 

 true frogs, have smooth 

 skin, and teeth in the up- 

 per jaw. Rana contains 

 our species including the 

 bullfrog (JR. catesbianay 

 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, Hylidas. 



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

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

 omosternum; s, ventral part of scapula; st, 

 sternum ; x, xiphisternum. 



SUB-CLASS IV. GYMNOPHIONA 



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

 amphicoelous ; 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 



