2650 FROGS AND TOADS 



its metatarsal spur, it rapidly excavates hollows in the ground, throwing out the 

 earth backwards, and soon partially concealing itself. An aperture is, however, 

 always left to the excavation, and should the rays of the morning sun reach its 

 occupant, the burrow is quickly deepened. In its movements the toad frog is more 

 active than the toads, approaching in this respect the frogs, as it takes considerable 

 leaps, swims strongly, and burrows with rapidity. The breeding season takes 

 place in April, during which time the males utter a loud croaking accompanied in a 

 lower tone by the females. The eggs are laid in strings of about a couple of feet in 

 length; and are taken from time to time by the male and carefully deposited round 

 reeds, grass, or other plants growing near the edge of the water. In from five to 

 six days the small black tadpoles are hatched out; and in the course of four months 

 these have completed their development and leave the water. When an adult toad 

 frog is suddenly seized or pinched, it utters a cry like the mewing of a kitten, at the 

 same time emitting a pungent vapor with a strong odor of garlic, both these being 

 apparently intended as a means of defense. 



Of the remaining genera, Pelodytes, as represented by the punctured 

 toad frog (P. pundatus) of Western Europe, and the Papuan Batra- 

 chopsis, differ from, the preceding in that the sacral vertebra has two condyles for 

 articulation with the rod forming the termination of the backbone, the hind-toes 

 being slightly webbed. In the Oriental genus Leptobrachium, there is but a single 

 condyle for the articulation of the rod-like bone. 



In the Miocene rocks of Europe there occur remains of numerous 



frogs which are assigned to an extinct genus, Palceobatrachus , regarded 



as representing a family {Pal&obatrachidce) connecting the present one 



with the under-mentioned Xenopodidce . In these extinct forms the upper jaw is 



toothed, the transverse processes of the sacral vertebra have expanded extremities; 



the sacral vertebra articulates with the terminal rod of the backbone by means of 



two condyles; the vetebrse have their articular cup in front; and there are no ribs. 



THE DlSC-TONGUED FROGS 



Family DlSCOGLOSSIDJE 



The disc-tongued frogs, as the members of this group may be called, form a 

 small family represented by four genera and seven species, inhabiting the northern 

 half of the Old World and New Zealand. As a family, these frogs are characterized 

 by the presence of teeth in the upper jaw, the expansion of the processes of the 

 sacral vertebra, the presence of short rudimentary ribs, and the circumstance that 

 in the bodies of the vertebrae the articular cup is placed at the hinder end, and the 

 ball in front. In both the latter respects these frogs resemble the salamanders and 

 newts, and they may accordingly be regarded as some of the least specialized repre- 

 sentatives of the order. Their remains occur abundantly in the middle Tertiary 

 rocks of Europe. The family derives its name from the disc-like form of the 

 tongue, which may be either free or adherent. From all the forms hitherto 



