Rock hen. Cornish hen. Cornish game hens are immature chickens of a breed of chicken that originated in Cornwall but gained popularity once it moved to the United States. Its body shape is quite different from that of other chickens. Both males and females have short legs and plump, muscular breasts. Although relatively slow-growing, the Cornish hen has excellent meat qualities. Its cross with the fast-growing Plymouth Rock chicken is responsible for most of the broiler and frier types currently on the market in the United States. An increasingly popular form of Cornish poultry, marketed for its delicious meat, is the Rock Cornish game hen which is a cross between Cornish and Rock hens. The Rock Cornish game hen was originally bred by Jacques and Alphonsine Makowsky in Connecticut in 1950. Said to have been bred as a temporary substitute for a flock of guinea hens lost in a fire at their farm, it soon became more popular than the guinea hen. The Rock Cornish is a standard meat-type chicken of a smaller size with all white meat, enough for a single serving. As is common in the poultry industry, store-bought game hens may be either male or female specimens, despite the common usage of the word "hen" typically denoting a female. Despite the name, game hens are not hunted as a game animal, and are raised in chicken coops as are normal chickens. The U.S. Department of Agriculture requires that all chickens sold as Cornish game hens be no more than 2 pounds in ready-to-cook weight.