ARBOREAL RICE RATS — ^HERSHKOVITZ 561 



slightly larger size, and, more significantly, by its narrower supra- 

 orbital region and weaker temporal ridges. 



Specimens examined: Twenty-three, from the following localities: 

 Brazil: Santa Ana de Chapada, Mato Grosso, 1 (BM, the type of roberti); 

 Descalvados, Mato Grosso, 1 (CNHM); Urucum de Corumbd, Mato Grosso, 1 

 (CNHM). 



Bolivia: "Mosetenes," Cochabamba, 1 (BM, type of mamorae); Todos Santos, 

 Cochabamba, 10 (AMNH, 5; CNHM, 5); Buenavista, Santa Cruz, 6 (CNHM, 5; 

 MACN, 1); Rfo Yapacani, Santa Cruz, 1 (MACN); Marbdn, Rio Mamor^, 

 Santa Cruz, 1 (MACN); Ticucha, Rio Capirenda, Chuquisaca, 1 (CNHM). 



Oryzomys concolor bahiensisy new subspecies 



Mus cinnamomeus Pictet and Pictet, Notices sur les animaux nouveaux ou peu 

 connus du musee de Geneve, p. 64, pi. 19 (animal), pi. 23, fig. 5 (molars), 

 1844 (type locality, Bahfa, Brazil; name preoccupied by Mus cinnamomeus 

 Lichtenstein, 1830, Darstellung neuer oder weniger bekannter Saugethiere, 

 Berlin, pi. 36, fig. 2 [=Proechimys myosuros Lichtenstein]). 



Oecomys cinnamomeus, Moojen, Os roedores do Brasil, p. 53, 1952 (Ilh^us, Bahfa, 

 Brazil) . 



Type: Adult male, skin and skull (CNHM 63780) collected 

 Sept. 19, 1944, by the Servigo de Estudos e Pesquisas Sobre a Febre 

 Amarela; original number M 19330. 



Type locality: Fazenda Almada, Ilheus, Bahia, Brazil. 



Distribution: Known only from eastern Bahia, Brazil, but 

 possibly ranges south into Minas Gerais and north and west into 

 the Rio Sao Francisco basin. 



Characters: Darker throughout than concolor; upperparts tawny, 

 underparts gray with a buffy wash, the slaty basal portions of the 

 hairs of belly, chest and limbs showing through; supraorbital region 

 broad, the ridges well developed and ledge-like. 



Measurements: Of the type and paratype, respectively, as follows: 

 Head and body, 140, 130; tail, 145, 150; hind foot, dry with claw, 

 27, 28; weight, — , 57 grams; greatest length of skull, 33.0, 36.6; 

 zygomatic breadth, 18, 16.7; width of rostrum, 5.9, 6.0; nasals, 11.7, 

 11.5; incisive foramina, 6.0, 5.9; diastema, 8.0, 7.9; alveolar length of 

 molar row, 5.3, 5.3; zygomatic plate, 3.8, 3.4. 



Measurements of the type of cinnamomeus Pictet and Pictet, given 

 in the original description, are as follows: head and body, 148; tail, 

 121; hind foot, 27. 



Remarks: In the type, the upperparts are ochraceous tawny 

 mixed with the dark brown of the guard hairs ; a faint ochraceous buff 

 lateral line is present ; belly and underside of limbs gray, washed with 

 buff, the slaty basal portion of the hairs showing through; posterior 

 half of chest like belly, anterior portion and throat nearly pure white ; 

 tail brown, upperside of metacarpus and metatarsus brownish, digits 

 silvery gray. A paratopotype is hardly distinguishable from the type. 



504676 — 59 i 



