The pool frog (Pelophylax lessonae) is a European frog in the family Ranidae. Its specific name was chosen by the Italian herpetologist Lorenzo Camerano in 1882, in order to honour his master Michele Lessona. Pool frogs are brown or green, with dark blotches along their backs, a pair of ridges running from each eye and a distinctive yellowy-green stripe down the middle of the frog's back. The vocal sacs on the male are cream or even white. The northern pool frog only occurs in the breckland area of East Anglia,England, and in a small number of other northern European countries (Sweden, Finland, Norway and Estonia). Its more widespread relative, the southern pool frog that occurs throughout a large region of central, southern and eastern Europe into Russia.