Observations on Mexican Rana pipiens

Mexican Rana pipiens now commonly sold in the United Statesdiffer morphologically and physiologically from their northerncounterparts. They resemble Arizona pipiens in appearance andbehavior, but their breeding cycle is distinctive. They aremost reproductively active in July and August. During late springand summer they can be ovulated readily and their pituitarygonadotropin levels are apparently high. Such is not the caseduring other times of the year. The role of Mexican frogs inteaching and research is discussed.