Polymely in a Frog

Abstract

THE male frog (Rana temporaria) described here was found in a batch of frogs from Cornwall (January 1950) which had been killed before the supernumerary limb had been noticed. This supernumerary left fore limb was situated behind the normal fore limb and articulated with the sternum (Figs. 1 and 2). Bateson¹ records frogs with supernumerary limbs and O'Donoghue² gives a short summary of the types of supernumerary fore limbs found in frogs up to 1910. Including his own two specimens, O'Donoghue cites thirteen frogs with either one or two supernumerary fore limbs; of these only one (listed, but not described, in the catalogue of the Royal College of Surgeons, 1872) had the supernumerary limb attached to the sternum. Wagner³ describes a specimen with three extra but imperfect fore limbs (two right and one left) attached to “an extra basal piece overlying the sternum”. Cotton⁴ records a specimen with an extra right fore limb immovably articulated with an imperfect extra half pectoral girdle. Therefore, so far as I know, the present is the only specimen described with a “sternal glenoid cavity”.