Mr. Nathaniel H. Bishop met with _cunicularia_ on the banks of the river San Juan, in Banda Oriental, where a few pairs were seen, devouring mice and insects. After crossing the river Las Vacas, and coming upon a sandy waste covered with scattered trees and low bushes, he again encountered it. Upon the pampas of the Argentine Republic they were found in great numbers, from a few miles west of Rosario to the vicinity of San Luis, where the pampas end. On these immense plains of grass it lives in company with the Bizcacha (_Lagostomus trichodactylus_), dwelling with it in perfect harmony, and during the day, while the animal is sleeping, a pair of Owls stand a few inches within the main entrance of the burrow, and at the first sound, be it near or distant, leave their station and remain outside the hole, or upon the mound that forms the roof of their domicile. At the approach of man, both birds, with their irides dilated, mount above him in the air, and keep up an alarm-note until he passes. Then they quietly settle down in the grass, or return to their former place. On the pampas Mr. Bishop did not observe them taking their prey during the daytime, but as soon as the sun had set, the Bizcacha and Owls both leave their holes in search of food, the young of the former playing about the birds as they alight near them. They do not associate in companies, there being but one pair to a hole. Each couple keep separate from their neighbors, and at night do not stray from their homes.