Frog

FROG, a name of wide application, strictly for an animal belonging to the family Ranidae, but also used of some other families of the order Anura of the class Amphibia (q.v.).

Frogs proper are typified by the common British species, Rana tem poraria, the edible frog, R. esculenta, and the American bull frog, R. catesbiana. The genus Rana includes in all about 200 species, distributed over the whole world with the exception of the greater part of South America and Australia. Some of the species are permanently aquatic and have fully webbed toes, others are terrestrial, except during the breeding season, others are adapted for burrowing, by means of the much-enlarged and sharp-edged tubercle at the base of the inner toe, while not a few have the tips of the digits dilated into disks by which they are able to climb on trees. The tree-frogs, Hylidae, show in their anatomical structure a close resemblance to the toads, Bu f onidae.

Some frogs grow to a large size. The bull-frog of eastern North America grows to nearly 8 in. from snout to vent, R. guppyi of the Solomon Islands to 81 in. and R. goliath, the South Cameroons to 10 inches. Among species belonging to other genera of the family may be mentioned the hairy frog of West Africa, Tricho batrachus robustus, some specimens of which have the sides of the body and of the hind limbs covered with long villosities and its ally Gampsosteonyx batesi, in which the last phalanx of the fingers and toes is sharp and claw-like and perforates the skin. To this family also belongs the arboreal genus Rhacophorus of eastern Asia, some species of which are remarkable for the ex tremely developed webs between the fingers and toes, which are believed to act as a parachute (flying-frog of A. R. Wallace), while others have been observed to make aerial nests between leaves overhanging water, a habit which is shared by their near allies, the Chiromantis of tropical Africa. Dimorphognathus, from West Africa, is the unique example of a sexual dimorphism in the dentition, the males being provided with a series of large sharp teeth in the lower jaw, which in the female is edentulous. The curious horned frog of the Solomon Islands, Ceratobatrachus guentheri, has teeth in the lower jaw in both sexes, while a few forms, such as Dendrobates and Cardioglossa, have no teeth at all.

in botany, the English name for a small rootless plant with floating leaves known botanically as Hydrocharis Morsus-ranae, a member of the family Hydrocharitaceae. The plant has rosettes of roundish floating leaves, and multiplies like the strawberry plant by runners, at the end of which new leaf rosettes develop. Staminate and pistillate flowers are borne on different plants; they have three small green sepals and three broadly ovate white membranous petals. The fruit, which is fleshy, is not found in Great Britain. The plant occurs in ponds and ditches in England and is rare in Ireland.

or MOREPORK, an Australian bird (Po dargus cuvieri), so-called from its cry, resembles the nightjar (q.v.) in appearance and habits and belongs to the same order, Coraciiformes. Some 24 species of the Podargidae are distributed from Southern India to Australia.