1849. _Sciurus migratorius_ Audubon and Bachman, Quad. N. Amer., 1:265 (based on _S. leucotis_ Gapper).
1877. _Sciurus carolinensis_ var. _leucotis_, J. A. Allen, Monogr. N. Amer. Rodentia, Sciuridae, p. 700 (_et auct._).
Two specimens (36192/48550, a young male with unworn teeth, and 36193/48551, an adult male with much worn teeth, both in the United States Biological Surveys Collection in the National Museum) were recorded by Bailey (N. Amer. Fauna, 25:75, 1905) as _Sciurus ludovicianus_ from Gainesville, Texas. Bailey (_loc. cit._) further stated that if the name _Sciurus rufiventer_ Geoffroy proved usable it would apply to the specimens from Gainesville. Since the name _rufiventer_ was revived there would be no question concerning the identity of these specimens had not Lowery and Davis (Occas. Papers, Mus. Zool., Louisiana State Univ., 9:172, 1942) assigned three specimens (not seen by us) to _Sciurus niger limitis_ Baird from a point only thirteen miles northwesterly. Lowery and Davis (_loc. cit._) say that their specimens are intergrades (presumably with _rufiventer_) and Bailey (_loc. cit._) noted that his two specimens from Gainesville "are in size and color nearer to _ludovicianus_ [= _rufiventer_] than to typical _limitis_." Examination of the two specimens from Gainesville convinces us that Bailey was correct and the specimens therefore are referable to _Sciurus niger rufiventer_. More in detail, the color agrees with that of _rufiventer_ and differs from that of _limitis_ and from that of darker specimens of _Sciurus niger ludovicianus_ (in the restricted sense used by Lowery and Davis, _op. cit._: 104). Also the size is larger than in _limitis_ and as in _rufiventer_ or _ludovicianus_. Selected measurements of Nos. 36192/48550 and 36193/48551 are, respectively, as follows: Total length, 505, 500; length of tail, 237, 228; length of hind foot, 72, 70; basilar length of Hensel, 48.5, 48.6; zygomatic breadth, 35.1, 36.0; length of nasals, 21.4, 22.3; alveolar length of maxillary tooth-row, 11.8, 11.1; width across posterior tongues of premaxillae, 17.5, 18.4.
Harris (Occas. Papers Mus. Zool., Univ. Michigan, 266:1, June 28, 1933) named _Sciurus variegatoides austini_ with type locality at Las Agujas, Province of Puntarenas, Costa Rica. Later, in his revision of the species _Sciurus variegatoides_, he (Misc. Publs. Mus. Zool., Univ. Michigan, 38:19, September 7, 1937) referred specimens from Chomes, Costa Rica, to _S. v. austini_ and (_op. cit._:24) specimens from Puntarenas, Province of Puntarenas, to _S. v. rigidus_, an inland subspecies. The geographic arrangement of these referred specimens seemed to warrant a reconsideration of the material. We have examined specimens of _S. variegatoides_ in the Museum of Zoology, University of Michigan, from the following localities in Costa Rica: Puntarenas (62703-62706), Las Agujas (65118 [type of _S. v. austini_], 59847-59850), Río Las Agujas (65114-65117), Agua Caliente (66483), Zarcéro (75757-75761, 75765), Cartago (67546, 67547), and Esparta (75762-75764). The specimens listed by Harris (_op. cit._, 1937:19) as from Chomes, in the Museum of Zoology of the University of Michigan, are not now in that museum and we have not seen them.