Part 21

Diagnosis.--Aristiforms wide; color on setiforms Ochraceous-Tawny on upper parts and sides; incisors orthodont; molariform teeth with one counterfold, p4 rarely with two.

Pelage.--Aristiforms on middorsal region: Lanceolate aristiforms, with basal part whitish, gradually blackening toward tip; total length, 25 to 28 mm; maximum width, 1.2 mm; clavate aristiforms with base whitish, gradually blackening toward tip but interrupted by Ochraceous-Tawny, subapical zone. Aristiforms on outer thighs: Whitish on basal half, gradually blackening toward tip; total length, 24 to 26 mm; maximum width, 0.9 mm. Some are whitish basally, gradually blackening toward distal part but distal fourth or fifth near (15'j) Ochraceous-Tawny. Setiforms on middorsal region: Whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Tawny, subapical zone; total length, 20 to 23 mm; maximum width, 0.1 mm. Some setiforms almost completely whitish. Setiforms on outer thighs: Whitish basally, gradually blackening toward tip but interrupted by near (15'j) Ochraceous-Tawny, subapical zone; total length, 18 to 20 mm; maximum width, 0.06 mm.

Skull.--Narrow; bullae small and smooth; jugals dorso-ventrally wide with conspicuous transverse ridge; postorbital process of zygoma well-developed and formed by jugal and squamosal; posterior palatine foramina obsolete; incisive foramen narrow and short; vomerine sheath complete or incomplete but premaxillary part at a level lower than that of maxillary part (when skull is viewed from ventral face); mesopterygoid fossa extending forward as far as anterior borders of second molars.

Teeth.--Incisors orthodont; molariform teeth with only one counterfold, except that p4 rarely has two counterfolds.

Comparisons.--From P. a. sertonius, albispinus differs in: sides of body darker; incisors orthodont as opposed to proodont; p4 rarely with two counterfolds instead of always with one counterfold.

Remarks.--The localities where P. a. albispinus has been collected have a forest climax with a moderate percentage of deciduous trees.

Specimens examined.--Total number, 19 (18 CNHM, 1 MCZ), from Brazil, Bahia, Andaraí, Macaco Seco.

=Proechimys albispinus sertonius= Thomas

Proechimys albispinus sertonius Thomas, July, 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):142 (orig. descr.); 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.

Type locality.--Lamarão ("about 70 miles north of Bahia City"), Ituiutaba, Bahia, Brazil; altitude 300 meters. Type: British Museum (Nat. Hist.), no. 3.9.5.86, adult male; collected on 16 June, 1903, by Alphonse Robert; original number, 1508.

Range.--Known from the type locality and Bonfim; probably occupies valleys of Jacuipe and the Itapicurú rivers and littoral between them.

Diagnosis.--Aristiforms wide; color of setiforms Ochraceous-Tawny on back, grading to Ochraceous-Buff on sides; incisors proodont; no molariform tooth with more than one counterfold.

Pelage.--Aristiforms on middorsal region: Lanceolate aristiforms whitish basally, gradually blackening toward tip; total length, 23 to 27 mm; maximum width, 1.3 mm. Clavate aristiforms, and some lanceolate ones, whitish basally, gradually blackening toward tip but interrupted by Ochraceous-Tawny, subapical zone. Some clavate aristiforms without subapical zone but blackened in distal part; total length, 23 to 24 mm; maximum width, 0.7 mm. Aristiforms on outer thighs: Whitish basally, gradually blackening toward tip but interrupted by Light Ochraceous-Buff, subapical zone; tip slightly darker; some whitish basally, grayish in middle and light yellowish toward tip; total length, 20 to 22 mm; maximum width, 0.9 mm. Setiforms on middorsal region: Whitish basal part succeeded by grayish, then by long, light, yellowish band, which becomes Light Ochraceous-Buff, and blackish tip; total length, 26 to 29 mm; maximum width, 0.15 mm. Setiforms on outer thighs: Whitish basal part succeeded by grayish, then Light Ochraceous-Buff, subapical zone and blackish tip; total length, 18 to 20 mm; maximum width, 0.13 mm.

Skull.--Broad; bullae small and smooth; jugals dorso-ventrally "wide," with conspicuous transverse ridge; postorbital process of zygoma well-developed and formed by both jugal and squamosal; incisive foramen narrow and short; vomerine sheath incomplete or complete but premaxillary part on a lower level than maxillary part (when skull is viewed from ventral face); mesopterygoid fossa extending forward as far as anterior faces of second molars.

Teeth.--Incisors proodont; molariform teeth with only one counterfold.

Comparisons.--Differences from P. a. albispinus are given in the account of that subspecies.

Remarks.--Localities where samples were collected are typical "caatinga" forest, a climax of mainly deciduous trees; cacti are also common in the region.

Specimens examined.--Total number, 10, from Brazil, Bahia, as follows: Ituiutaba, Lamarão, 4 (1 DZ, 1 CNHM, 1 MCZ, 1 USNM); Bonfim, Bonfim, 6 (5 DZ, 1 MN).

INCERTA SEDIS

=Proechimys myosuros= (Lichtenstein)

Loncheres myosuros Lichtenstein, 1818, Das zoologische Museum der Universität zu Berlin, (2):18 (nomen nudum); Lichtenstein, 1820, Abhandl. K. Akad. Wissensch., Berlin (1818-1819):192, pl. 1, fig. 2 (orig. descr.); Wied, 1826, Beiträge zur Naturgeschichte von Brasilien, 2:445.

Mus leptosoma Brants, 1827, Het geslacht der Muizen door Linnaeus opgesteld ..., Berlyn, p. 150; Lichtenstein, 1830, Darstellung neuer oder wenig bekannter Säugethiere, Berlin, Heft 7, pl. 36, fig. and text pages.

Mus cinnamoneus Lichtenstein, 1830, Darstellung neuer oder wenig bekannter Säugethiere, Berlin, Heft 7, pl. 36.

Echimys myosuros Is. Geoffroy Saint-Hilaire, 1838, Comptes Rendus Acad. Sci., 6(26):886, and 1840, Mag. Zool., Paris (ser. 2, année 2):15, 33, 53; Allen, 1899, Bull. Amer. Mus. Nat. Hist., 12(20):261.

Echinomys leptosoma Wagner, 1843, Schreber's Säugethiere, suppl., 3:341.

Echinomys myosuros Burmeister, 1854, Syst. ubersicht Thiere Brasiliens, p. 199.

Proechimys setosus Thomas, 1921, Ann. Mag. Nat. Hist., 8 (ser. 9):141.

Proechimys myosuros 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.