_Records of occurrence._--Specimens examined, 53: San Fernando, 180 ft., 5; 9-1/2 mi. SW Padilla, 800 ft., 3; Rancho Santa Rosa, 25 km. N, 13 km. W Cd. Victoria, 260 m., 8; 3 mi. NE Guemes, 5; Soto la Marina (3 mi. N), 500 ft., 6; Sierra de Tamaulipas, 10 mi. W, 8 mi. S Piedra, 1200 ft., 6; 43 km. S Cd. Victoria, 1; Ejido Santa Isabel, 2 km. W Pan-American Highway, 2000 ft., 5; 70 km. (by highway) S Cd. Victoria, 6 mi. W of Pan-American Highway, 3; 2 mi. W El Carrizo, 7; Rancho Pano Ayuctle, 6 mi. N Gómez Farías, 300 ft., 2; Rancho Pano Ayuctle, 25 mi. N, 3 km. W El Mante, 300 ft., 1; 8 km. W, 10 km. N El Encino, 400 ft., 1. Additional records: Río Corono (= Corona) (J. A. Allen, 1891:222); Victoria (Kelson, 1952:249); Santa María (Goodwin, 1954:8); 3 mi. NW Acuña, 3500 ft. (Hooper, 1953:4); Forlón (Nelson, 1899:42); NE Zamorina (Hooper, 1953:4); Gómez Farías (Goodwin, 1954:8); Altamira (Nelson, 1899:42); Tampico (J. A. Allen, 1891:222). =Sciurus deppei negligens= Nelson Deppe's Squirrel 1898. _Sciurus negligens_ Nelson, Proc. Biol. Soc. Washington, 12:147, June 3, type from Altamira, Tamaulipas. 1953. _Sciurus deppei negligens_, Hooper, Occas. Papers Mus. Zool., Univ. Michigan, 544:4, March 25. _Distribution in Tamaulipas._--Tropical forest in southern part of state, north to Rancho Santa Rosa and Padilla. In Tamaulipas this squirrel is called "ardilla chica" or "ardilla barcina," and is abundant in areas where tall trees and dense brush prevail. This species evidently does not have restricted periods of activity, as does _S. aureogaster_, but is active throughout the day. At El Carrizo a nest, nine to 10 inches in diameter and constructed of leaves and small sticks, was in a thick tangle of branches 25 feet above the ground. A male having testes 11 mm. long was in the nest. Among 16 females collected in the months of February, May and June, only two, taken in February, were lactating. A female from 70 kilometers south of Ciudad Victoria, had four placental scars, three on the right side and one on the left, along with a resorbed embryo on the right side; according to the collector "the scars appeared quite recent, as evidenced by the fact that not all of the blood had been resorbed yet." The northernmost localities from which _S. d. negligens_ has been reported are nine and a half miles southwest of Padilla in the east, and Rancho Santa Rosa in the west. Three males from the vicinity of Padilla weighed 309, 276, and 261 grams.