1042 



CLASS AMPHIBIA. 



triton is a large form from the Upper Eocene Phosphorites of 

 Central France. 



Order IV. Ecaudata. — The Frogs and Toads form a highly 

 specialised order of comparatively late origin. In the adult the 

 body is short, destitute of a tail, and furnished with four limbs, of 



Fig. 974. — A, Skeleton of the Frog {Rana temporarid) '. tr, Transverse processes of vertebras ; 

 sa, Sacrum ; ur, Urostyle ; z, Ilium ; s, Suprascapula ; b, Humerus ; ab, Radius and ulna ; c. 

 Carpus ; p, Pollex ; f, Femur ; cr, Tibia and fibula ; ca, Calcaneo-astragalus ; ta, Tarsus ; sp, 

 Prohallux. b, Pectoral arch and sternum of Frog (after Gegenbaur). The dotted parts represent 

 cartilages, e, Episternum ; o, Omosternum ; p, Body of the sternum ; x, Xiphisternum ; sc', 

 Suprascapula ; sc, Scapula ; cl, Precoracoid ; co, Coracoid ; s, Epicoracoid. 



which the pelvic pair is the longer, and adapted for leaping. There 

 are no gills. The skull is short and wide, with enormous orbits, 

 and the parietals confluent with the frontals. A peculiar ossification 

 known as the girdle-bone encircles the skull in the ethmoidal region, 

 and there is a predentary ossification in the mandible. The pre- 



