1911 Encyclopædia Britannica (1911)
“ Frogs proper are typified by the common British species, Rana temporaria, and its allies, such as the edible frog, R. esculenta, and the American bull-frog R. catesbiana. The genus Rana may be defined as firmisternal Ecaudata with cylindrical transverse processes to the sacral vertebra, teeth in the upper jaw and on the vomer, a protrusible tongue which is free and forked behind, a horizontal pupil and more or less webbed toes. It includes about 200 species, distributed over the whole world with the exception of the greater part of South America and Australia. ”
