The Edible Frog attains to a rather larger size than the Common Frog. It is usually without the dark patch extending from the eye to the shoulder, and the markings of the body--especially the bright yellow and black marblings of the hinder parts--are darker and bolder. There is usually a light yellow or green line running down the middle of the back from the muzzle to the hinder extremity. The most distinctive feature, however, is restricted to the male sex: at the hinder angle of the mouth, just below the ear, are external vocal sacs which, when the owner is inclined to be melodious, become distended with air to the size of large peas, giving him a very quaint appearance. The croak differs from that of the Common Frog, and has been described as "more of a loud snore, exactly like that of the Barn Owl;" but this probably refers to the vocal efforts of the female, for Bell says it is so loud and shrill as to have obtained for the frogs the names of "Cambridgeshire Nightingales" and "Whaddon Organs." The males continue to "sing" after the breeding season is past, particularly on warm moonlight nights, when they may be heard for over a mile when the choir consists of several hundred voices. The notes are "Brekeke, gwarr, ooaar, coarx." To return to a description of the Edible Frog. Full-grown examples measure from two and a half to four inches of head and body; the females larger than the males. The head is more slender than in the Common Frog, and the brown eardrum is two-thirds of the diameter of the eye. The teeth on the palate form two oblique lines; and there is a pair of glandular folds behind the eye. The ground colour of the upper parts ranges from dull brown through olive to bright green, with dark brown or blackish spots on the back and larger patches of similar tint on the limbs. There is usually a bronzy-brown line along each side of the back, in addition to the central one already named. The back of the thigh is always spotted with black and white or yellow. Though the thigh of the Common Frog is barred or blotched, it never bears these additional spots. The coloration generally is much brighter where the vegetation is light than in dark swamps with sombre vegetation.