NARROW-MOUTHED GROUP. 273 



throat-sac of the males being enlarged and modified so as to form an extensive 

 chamber on the under surface of the body in which the eggs and tadpoles undergo 

 their development. This chamber is entered by two apertures situated on the 

 floor of the mouth on each side of the tongue ; and when the eggs, generally from 

 eleven to fifteen in number, are laid by the female, they are taken and swallowed 

 by her consort, who passes them into his pouch. When the tadpoles are sufficiently 

 developed, they enter the world by escaping through the parental mouth. It 

 appears that at no stage of their existence do the tadpoles possess external gills. 



THE SHARP-NOSED FROG. 

 Family CERATOBATRACHID^. 



Omitting detailed mention of the small and unimportant family of the 

 Discophidce, characterised by the presence of teeth in the upper jaw, and the 

 expansion of the extremities of the transverse processes of the sacral vertebra, our 

 last representative of the first suborder is the sharp-nosed frog (Ceratobatrachus 

 guentheri), of the Solomon Islands, which constitutes a family by itself. The 

 essential characteristics of the family are the presence of teeth in both the upper 

 and lower jaws (a feature found elsewhere only in two families of the next 

 suborder), coupled with the absence of expansion of the extremities of the sacral 

 vertebrae. This frog has a very large triangular head, ornamented with prominent 

 ridges, and terminating in front in a pointed flap of skin ; similar flaps occupying 

 the eyelids, and the mouth having an enormous capacity. In the eye the pupil is 

 horizontal ; and teeth are present on the vomers. The hind-limbs are rather short ; 

 and all the toes have simple terminations, and are devoid of webs. In colour this 

 curious frog is very variable. Although very little is known as to its habits, it 

 appears to be abundant in the Solomon Islands ; and it is remarkable for laying 

 very large eggs, from which the young emerge nearly fully-developed. 



THE SOUTHERN FROGS. 

 Family LEPTODACTYLID^E. 



In the greater part of South America and the whole of Australia the typical 

 frogs are replaced by a family which, for want of a better name, we may call the 

 southern frogs. These, together with seven other families, differ essentially from 

 the forms hitherto considered, in regard to the conformation of the bones of the 

 chest, and thus collectively constitute a second suborder, known as the Arcifera. 

 It will be remembered that in the preceding suborder the two metacoracoid bones 

 are connected together by a single cartilage joining their free edges ; in the present 

 group each metacoracoid terminates in a large cartilage, in such a manner that one 

 cartilage overlaps its fellow of the opposite side. The southern frogs resemble the 

 typical frogs in having the upper jaw alone toothed, and in the transverse processes 

 of the sacral vertebra being cylindrical or but slightly expanded, while they also 

 agree in the characters of the vertebrse and the absence of ribs. It is thus evident 



VOL. v. 1 8 



