In the field notes of Professor Joseph Beal Steere, an entry for no. 72 reads: "Big white bellied wood rats x two young found in nest of grass on the ground with the two young--_much darker_ young female." No. 77 in his field notes corresponds to the type specimen. _Specimens examined._--Total number, 4, from Brazil, as follows: Amazonas. _Lábrea_, Hyutanaham, 3 (USNM); Territ. Guaporé, Porto Velho, 1 (CNHM). =Proechimys goeldii goeldii= Thomas _Proechimys goeldii_ Thomas, June 1905, Ann. Mag. Nat. Hist., 15 (ser. 7):587, (orig. descr.); Thomas, 1912, Ann. Mag. Nat. Hist., 9 (ser. 8):89; Thomas, 1920, Ann. Mag. Nat. Hist., 6 (ser. 9):277, Tate, 1935, Bull. Amer. Mus. Nat. Hist., 68(5):400; Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist., 29(13):199. _Proechimys cayennensis goeldii_, Ellerman, 1940, The families and genera of living rodents, Brit. Mus. (Nat. Hist.), 1:121. _Type locality._--Santarem, _Santarem_, Pará, Brazil. Type: British Museum (Nat. Hist.), no. 5.1.25.6, adult female; presented by Dr. E. A. Goeldi. _Range._--Margins of the Amazon, between Jamundá and Tapajoz rivers. _Diagnosis._--Upper parts Ochraceous-Tawny; wide across zygomata; nasals of moderate length; incisive foramen long and narrow; vomerine sheath complete but maxillary part slender; first and second upper molars with four counterfolds. _Pelage._--_Aristiforms on middorsal region_: Whitish basally and gradually blackening toward tip which is extended as long, thin filament; total length, 22 to 24 mm; maximum width, 0.5 mm. _Setiforms on middorsal region_: Gray basally, gradually blackening toward tip but interrupted by Ochraceous-Tawny, subapical zone 3.3 mm long; total length, 19 to 21 mm; maximum width, 0.06 mm. _Setiforms on outer thighs_: Whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Tawny, subapical zone 3 mm long; total length 14 to 16 mm; maximum width, 0.04 mm. _Skull._--Large and strong; nasals pointed posteriorly; supraorbital ridges moderately developed and extended caudad across anterior third of parietals; zygomatic arches strong; postorbital process of zygoma involving mostly squamosal; incisive foramen elongate and narrow (5 to 6.5 x 2.3 mm) with margins more or less parallel and raised to form ridges which extend posteriorly to within 3 mm of plane of premolars; vomerine sheath complete, with maxillary part thin and extended caudad as medial crest; mesopterygoid fossa extending forward as far as posterior faces of second molars or slightly short thereof; bullae large and inflated.