Ears of ground squirrels to show characters of size and shape in different species, "a", California Ground Squirrel ("Spermophilus beecheyi beecheyi"); "b", Fisher Ground Squirrel ("Spermophilus beecheyi fisheri"); "c", Oregon Ground Squirrel ("Spermophilus beldingi oregonus"); "d", Stephens Soft-haired Ground Squirrel ("Spermophilus mollis stephensi"); "e", Mohave Ground Squirrel ("Spermophilus mohavensis");, Yuma Round-tailed Ground Squirrel ("Spermophilus tereticaudus tereticaudus"); "g", Sierra Golden-mantled Ground Squirrel ("Callospermophilus lateralis chrysodeirus"); "h", Desert Antelope Ground Squirrel ("Ammospermophilus leucurus leucurus"). All natural size and drawn direct from specimens. Note: "a" and "b" are extreme examples ; the average difference existing between the California and the Fisher ground squirrels is much less; individuals of each race can be found which will overlap some individuals of the other in size and shape.