TOAD-FROGS. 283 



number, appear to be placed in the pouch by the male, who employs his hind-feet 

 for the purpose ; and they are remarkable for the large relative size of the yolk. 

 The tadpoles, when first hatched, are peculiar in having a bell-shaped structure for 

 the protection of their two pairs of external gills. 



THE TOAD-FROGS. 

 Family PELOBATIDJE. 



The fifth family of the order belonging to the section with overlapping 

 cartilages to the metacoracoids comprises eight genera, which may be collectively 

 termed toad-frogs, since they come neither under the designation of toads or frogs. 

 Agreeing with the tree-frogs in the presence of teeth in the upper jaw, they may 

 be distinguished by the much greater expansion of the processes of the sacral 

 vertebra, ribs being absent, and the terminal joints of the toes simple. In all 

 the forms the pupil of the eye is vertical ; and whereas the majority of the genera 

 agree with the preceding groups in having the articular cup at the front and the 

 ball behind, in a few this arrangement is reversed. The family is distributed 

 over Europe, the Oriental region, North America, and New Guinea ; the various 

 genera having a more or less restricted geographical range. 



Brown The brown toad-frog (Pelobates fuscus) is the typical representa- 



Toad-Frog. ^ive o f a genus containing two European species, neither of which are 

 found in Britain. They are characterised by the rod at the end of the backbone 

 being welded to the sacral vertebra, and by the extensive webbing of the hind-toes ; 

 the presence of a bony style to the breast-bone, coupled with the want of an 

 externally visible ear-membrane, serving to distinguish them from an allied North 

 American genus (Scaphiopus). The brown toad-frog is a rather large species, 

 usually measuring from 2J to 3 inches in length, and having a smooth brown skin, 

 marbled on 'the upper-parts with darker markings ; a spur which is present on the 

 metatarsus being yellowish brown. The males have no vocal sac, but are furnished 

 with a large elliptical gland on the upper surface of the fore-limb. This species 

 is decidedly local, and in some districts is replaced by the allied P. caltripes, easily 

 distinguished by the black spur on the metatarsus. Spending only a few days 

 during the breeding-season in the water, it is essentially a land animal, generally 

 frequenting spots with a sandy soil. Here, with the aid of 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 



