Article XXIV. NEW SOUTH AMERICAN MURID^E 

 AND A NEW METACHIRUS. 



BY J. A. ALLEN. 



Of the nine species described in the present paper eight are 

 based on material in the British Museum. 



In this connection I take the opportunity to express my appre- 

 ciation of the great kindness shown me by Mr. Oldfield Thomas, 

 Curator of Mammals, during a few weeks spent at the British 

 Museum the past summer, chiefly in the study of South American 

 Rodents. He not only allowed me unrestricted use of the 

 material under his charge, but greatly aided me in many ways in 

 my researches. The following descriptions of new species were 

 written in response to his generous solicitation. 



Oryzomys bolivaris, sp. nov. 



Type, No. 99-9-9-27, British Museum, $ adult, Porvenir, Bolivar, Ecuador, 

 altitude 1800 m., March 10, 1899 ; collected by P. O. Simons. Original No. 



251- 



Above medially very dark brown, punctated with ferruginous, the general 

 effect being what might be called dark chestnut brown ; sides lighter, more yel- 

 lowish brown, becoming gradually paler towards the ventral surface, which is 

 sharply defined and dull white, the fur being plumbeous at base and broadly 

 tipped with soiled white ; upper surface of fore and hind feet nearly naked, 

 dull flesh color, soles blackish brown ; ears rather small, dark brown ; tail 

 naked, pale brown, nearly unicolor. 



Measurements (of type and only specimen). Total length, 225 mm. ; head 

 and body, 125 ; tail, TOO ; hind foot, 29 ; ear, 18. 



The skull presents nothing distinctive ; it is rather narrow for its length, with 

 rather a broad postpalatal opening and rather large palatal foramina. The 

 teeth are of medium size, but in the single specimen are greatly worn. Total 



length, 30.2 ; basilar length, ; zygomatic width, 15.2 ; mastoid width, 12 ; 



postorbital width, 5.2 ; length of nasals, 12 ; length of palate, 6 ; palatal foram- 

 ina, 6 ; upper toothrow, 4.5 ; length of lower jaw, 16 ; height of condyle, 8.5 ; 

 lower toothrow, 4.8. 



This species is characterized by the dark color of the dorsal 

 surface, small ears, and tail considerably shorter than the head 

 and body. In coloration it somewhat resembles the S. magdale- 

 HCB group, but the general effect is much darker and more border- 

 ing on dark chestnut than yellowish brown, but from which group 



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