In the collection of the American Museum of Natural History there is one specimen (AMNH no. 16140) of _Proechimys_, included in the so-called Maximilian Collection. The characters of this specimen agree closely with those of the specimens from Lagoa Santa. The locality of capture of specimen no. 16140 is unknown, but it is reasonable to assume that Prince Maximilian zu Wied obtained it somewhere along his route of travel through southeastern Bahia. Wied (1826:445) mentions "_L[oncheres]. myosuros_ Licht." as "am Parahyba, am Peruhype und Belmonte," which greatly increases the possibility of its having come from southern Bahia. The close similarity to _elegans_ of Wied's specimen indicates that the locality of capture possibly was in the region of the less humid, low escarpments of southern Bahia. My conclusion is that Wied's specimen corresponds closely to _setosus_ and, tentatively, I identify it as such. "_Echimys elegans_," due to the relationships mentioned above is here considered to be a subspecies of _setosus_. Among the species described in earlier times, and whose identity was never ascertained, _"Echinomys" fuliginosus_ Wagner seems to be synonymous with _setosus_. Wagner describes the animal as having a tail "apicis versus pilis albidis vestita" and the figure of the cheekteeth (1844, pl. 239 D) shows a typical trilaminate condition which occurs commonly in _elegans_. Moreover, the tail of _fuliginosus_ is only 9 per cent shorter than the head and body and the aristiforms of this subspecies are moderately wide. =Proechimys setosus setosus= (Desmarest) _Echimys setosus_ Desmarest (Geoffroy's MS), 1817, Nouv. Dict. Hist. Nat. nouv. ed., 10:59 (orig. descr.); Is. Geoffroy Saint-Hilaire, 1838, Comptes Rendus Acad. Sci., Paris, 6(26):886; Is. Geoffroy Saint-Hilaire, 1840, Mag. Zool., Paris, (ser. 2, année 2):12, 33, 52; Allen, 1899, Bull. Amer. Mus. Nat. Hist., 12(20):257, 261. _Echimys cayennensis_ Pictet, 1841, Mém. Soc. phys. Hist. Nat., Genève, 9:145; Waterhouse, 1848, Nat. Hist. Mammalia, 2:334. _Echinomys fuliginosus_ Wagner, 1843, Schreber's Säugethiere, suppl. 3:343; Wagner, 1844, Schreber's Säugethiere, suppl. 4, pl. 39 D. _Proechimys setosus_ Allen, 1899, Bull. Amer. Mus. Nat. Hist., 12(20):264; Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):141; Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):401; Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:122. _Proechimys fuliginosus_ Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5): 400; Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:119. _Type locality._--Unknown; see remarks under _P. setosus_. _Type_: Museum d'Histoire Naturelle, Paris, no. A. 7787 (Thomas, 1921:141), "very imperfect."