We have crossed the international border once more, this time driving to Nogales, Arizona, then across the street into Nogales, Sonora, looking for a well-known Prickly Pear growing on the grassy mesas and _bajadas_ of northern Sonora and of southern Arizona. Its name _discata_ refers to the large circular and disklike joints of the stems, nearly a foot in diameter and about half an inch thick, which form the many ascending and spreading branches of this shrub; and it seems to us we could almost use them in throwing the discus in the marvelous Olympiad Games to be held this summer, here in the giant amphitheater of the sun. The beautiful plants grow in large clumps about five feet high and five to ten feet across, standing forth as most striking figures on the desert canvas with their erect spreading pear-like arms and the vivid harmony of color in their large and brilliant blooms; glossy lemon-yellow shading into deep orange, then the yellow-green tints of the sepals and the cream-white suffused with a delicate pinkish cast of the club-like styles. There is a little animal living on the desert known as the trade rat or pack rat which invariably seeks the _Opuntia discata_ for building his home; if the habitat of this little rat is investigated about five bushels of débris will be found including cactus joints, stems, sticks, and even stones, all carefully piled away in and under these plants. This is a sure sign of the pack rat’s nest, for in such a home his needs are all taken care of; the _discata_ gives him protection from wandering coyotes and dogs, water and food in its succulent stems, and still more food in the ripe sweet fruit. The latter is covered with many fine spicules and the Indians skillfully remove these by rubbing, so as not to get the prickers into the fingers; for they are very annoying and irritating if they find their way into the flesh. The ripe fruit is gathered for food by Mexicans and Indians, who make from it a fine syrup, delicious preserves and other delicacies. [Illustration: ENGELMANN’S PRICKLY PEAR (Opuntia Engelmannii)] Engelmann’s Prickly Pear (_Opuntia Engelmannii_) _Northern Mexico, Arizona, and Texas_