254 ZYGODONTOMYS, SIGMODONTOMYS. 



SUERRE RICE RAT. 



Type locality. Suerre, Costa Rica. 



Geogr. Distr. Costa Rica, Central America. 



Genl. Char. Size medium ; tail half the length of head and body ; 

 ears small. Skull has the superciliary bead very broad; anterior 

 palatal foramina not reaching anterior base of the first molar. 



Color. Above mixed blackish brown and yellowish rufous; 

 brighter on the sides; under parts yellowish brown tinged with gray; 

 tail uniform black; hands and feet blackish brown; ears black. 



Measurements. Total length, 187; tail, 90; hind foot, 25; ear, 

 from notch, 10.5. Skull: total length, 28; basal length, 23.5; zygo- 

 matic breadth, 15; palatal length, 5.3; width of braincase, 12; length 

 of nasals, 9.5 ; length of upper tooth row, 5.3. (ex Type.) 



247. seorsus (Zygodontomys) , Bangs, Am. Nat., xxxv, 1901, p. 642. 

 ISOLATED RICE RAT. 



Type locality. San Miguel Island, Bay of Panama. 



Genl. Char. Similar to Z. brevicauda from Trinidad, but larger; 

 tail scales coarse; skull larger, characters more pronounced. 



Color. "Upper parts russet brown, shaded with dull ferru- 

 gineous, the latter more intense on the rump; whole dorsal region 

 thickly set with brownish black-tipped hairs; sides paler, more yel- 

 lowish; under parts dull buffy gray, strongly shaded with dull ferru- 

 gineous on anal region ; line of demarcation between colors of upper 

 and under parts indistinct ; upper surface of hands and feet yellowish 

 brown; soles naked; ears sparsely haired, dusky; tail very sparsely 

 haired, coarsely scaly, indistinctly bicolor, blackish, rather paler 

 towards base below." 



Measurements. Total length, 280-320; tail vertebrae, 110-140; 

 hind foot, 30-34; ear from notch, 15-18. Skull: basal length, 32.8; 

 occipito-nasal length, 35.2; zygomatic width, 18.4; mastoid width, 

 12.8; length of nasals, 15; width of nasals, 4.4; interorbital constric- 

 tion, 5.4; width across zygomatic plates, 11.2; length of incisive 

 foramina, 7.4; width of incisive foramina, 3.2; length of palate, to 

 palatal notch, 16; to end of pterygoid, 22 ; upper tooth row, 5.2 ; length 

 of single half mandible, 21 ; lower tooth row, 5.2." (Bangs, 1. c.) 



5 1 . Sigmodoiitomys. 



Sigmodontomys Allen, Bull. Am. Mus. Nat. Hist., 1897, p. 38, pi. 



i, figs. 8-14. Type Sigmodontomys alfari Allen. 

 Nasals narrowing posteriorly, pointed; anterior palatine foramina 

 broad, not reaching front molars; palate reaching beyond posterior 

 line of molars; palatal fossa broad, pterygoids parallel; base of 



