Part 8

(b) Tail 90 per cent or more of head and body; aristiforms evident on outer thighs and rump; skull with no ridges across parietals; size of upper cheekteeth decreasing from P4 to M3; main fold large. subgenus TRINOMYS, 5

2. (a) One or more upper molars with four counterfolds 3 (b) Upper molars with no more than three counterfolds, 4

3. (a) Aristiforms wide (more than 0.7 mm). P. semispinosus, p. 342 (b) Aristiforms narrow (less than 0.7 mm) P. goeldii, p. 338

4. (a) Aristiforms wide (0.9 mm or more), or narrow (0.6 to 0.7 mm) but then with only two counterfolds in each lower molar P. guyannensis, p. 355 (b) Aristiforms narrow (0.5 to 0.65 mm) but with one or more lower molars having three counterfolds. P. longicaudatus, p. 346

5. (a) Aristiforms narrow (0.5 mm) and limber; no differentiated light-colored aristiforms on outer thighs and rump; incisive foramen short and widest posteriorly P. dimidiatus, p. 371 (b) Aristiforms 0.6 mm or more and stiff; differentiated light-colored aristiforms on outer thighs and rump; incisive foramen elongated and constricted posteriorly 6

6. (a) Skull large, more than 50 mm in total length, incisors opisthodont P. iheringi, p. 373 (b) Skull small, less than 49 mm in total length, incisors orthodont or proodont 7

7. (a) No clavate aristiforms, tail with white tip, P. setosus, p. 384 (b) Clavate aristiforms among the ordinary ones, tail without white tip P. albispinus, p. 388

Subgenus =Proechimys= J. A. Allen

General characters.--Pelage with lanceolate aristiforms limited to an area on the dorsal surface between the shoulders and the hips; length of tail less than 90 per cent of length of head and body; skull with conspicuous ridges; extension of supraorbital ridges always evident on parietals; infraorbital foramen usually with separate groove for transmission of nerve; palate usually extended posteriorly as far as third molars; incisors opisthodont; molariform teeth with a small main fold, never extended transversely to opposite wall in occlusal surface of tooth; usually one counterfold anterior to main fold in upper molariform teeth and posterior to main fold in lower molariform teeth; premolars usually smaller than first molars, first molars smaller than second molars but second molars larger than third molars.

=Proechimys goeldii= Thomas

General characters.--Size large; tail short; aristiforms narrow and soft, usually concealed in pelage by setiforms; general color of upper parts some tint of orange, gradually becoming lighter on sides with no conspicuous, dark longitudinal band on back; feet dark; ventral surface of body and inner side of legs white but sometimes with some buff locally; skull broad and strongly built but not conspicuously ridged; zygomatic expanse great and rostrum not elongate; incisive foramen narrow; bullae large and inflated; upper molariform teeth with three to four counterfolds, M3 ordinarily with four; lower premolars with four, and molars with three, counterfolds.

=Proechimys goeldii steerei= Goldman

Proechimys steerei Goldman, Proc. Biol. Soc. Washington, 24:238, 28 November 1911 (original description); Goldman, 1912, Proc. Biol. Soc. Washington, 25:186; 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; Osgood, 1944, Zool. Ser. Field Mus. Nat. Hist., 29(13):204.

Type locality.--Hyutanaham, Upper Purus, Lábrea, Amazonas, Brazil. Type: United States National Museum, no. 105535, adult male; collected in 1901 by Prof. J. B. Steere.

Range.--Known only from the type locality and Porto Velho.

Diagnosis.--Upper parts Mars Orange on back, grading to Ochraceous-Tawny on sides; zygomatic breadth narrow; nasals short; incisive foramen narrow and short; vomerine sheath complete and thick; upper molars usually with four counterfolds.

Pelage.--Aristiforms on middorsal region: Grayish basally, gradually blackening toward tip; total length, 16 to 19 mm; maximum width, 0.5 mm. Setiforms on middorsal region: Grayish on basal third, gradually blackening toward tip but interrupted by a Mars Orange, subapical zone 1.5 mm long; total length, 16 to 19 mm; maximum width, 0.06 mm. Setiforms on outer thighs: Whitish basally, gradually blackening toward tip but interrupted by Orange Rufous or Ochraceous-Tawny, subapical zone; total length, 14 to 16 mm; maximum width, 0.05 mm.

Skull.--Large and strong; rostrum rather pointed posteriorly; supraorbital ridges not much expanded and extending across anterior half of parietals; infraorbital foramen without groove for transmission of nerve, or groove obsolete; zygomatic arches slender; postorbital process of zygoma involving mostly squamosal; incisive foramen short and narrow (4.5 × 2.5 mm) with margins almost parallel or tapering gradually caudad and extending toward palate as ridges; posterior margin of incisive foramen approximately 2.5 mm anterior to premolars; vomerine sheath complete, with both elements well-developed; mesopterygoid fossa never extending anterior to middle of M3; bullae large, well inflated and with shallow grooves.

Teeth.--Upper molariform teeth: P4 with three counterfolds; upper molars with four counterfolds each or, less commonly, three. Lower premolars with four counterfolds; lower molars with three each.

Comparisons.--From P. g. goeldii, steerei differs in: Back and sides with more reddish; narrower interorbitally and across zygomata; palatilar length less and nasals shorter; maxillary part of vomerine sheath thicker; usually four instead of three counterfolds in M3.

Remarks.--This subspecies is clearly related to P. goeldii. One skull from Porto Velho, Rio Madeira, Guaporé, Brazil (CNHM no. 21558) may belong to an unnamed subspecies but is provisionally included here.

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.