8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 56 



prolong-ed posteriorly beyond premaxillse ; dentition about as in 

 richmondi. 



Measurements. — Type : Total length, 224 mm. ; tail vertebrae, 115 ; 

 hind foot, 31.5; Skull (type) : Greatest length, 27.7; condylobasal 

 length, 24.8; zygomatic breadth, 14.5; nasals, 10.2; interorbital 

 breadth, 5.3; interparietal, 7.3 x 1.5; incisive foramina, 5.6; length 

 of palatal bridge, 5.2 ; maxillary toothrow, 5. 



Remarks. — This species seems to require comparison only with 

 richmondi. It is represented by a single specimen taken in an 

 abandoned sugar plantation on the bank of the Chagres River. 



ZYGODONTOMYS CHERRIEI VENTRIOSUS, subsp. nov. 



Type from Tabernilla, Canal Zone, Panama. No. 1 71098, male 

 adult, U. S. National Museum (Biological Survey Collection), col- 

 lected by E. A. Goldman, March 12, 1911. Original number 20975. 



General characters. — -Similar to cherriei, but larger ; general color 

 paler and grayer, the back more uniform, less distinctly darkened 

 along median line. 



Color. — Upper parts grayish brown, darkest and more or less 

 suffused with yellowish, or light rusty brown, on median dorsal 

 area, becoming paler and grayer along flanks and outer sides of 

 limbs ; under parts dull creamy white, or gray, the fur short, and the 

 plumbeous basal color showing through ; ears brownish, overlapped 

 at anterior base by rather long rusty hairs ; feet white ; tail nearly 

 naked, grayish above, whitish below. 



Skull. — About like that of cherriei, but larger. 



Measurements. — Type : Total length, 240 mm. ; tail vertebrae, 104 ; 

 hind foot, 28. Average of ten adult topotypes: 236 (220-255) ; 102 

 (94-109) ; 27.3 (26.5-28). Skull (average of four adults) : Great- 

 est length, 31.7 (30.5-32.5) ; condylobasal length, 29.6 (28.5-31) ; 

 zygomatic breadth, 16.4 (16-17.2) ; nasals, 12.2 (11. 2- 13. 5) ; inter- 

 orbital breadth, 5 (5-5.2) ; interparietal, y.y x 3 (6.3 x 3-9 x 3.5) ; 

 incisive foramina, 6.7 (6.2-7) ; length of palatal bridge, 5.5 (5.5- 

 5.5) ; maxillary toothrow, 4.6 (4.5-4.8). 



Remarks. — This form, representing the genus Zygodontomys in 

 the Canal Zone, seems to be the most abundant murine rodent in 

 the grassy clearings and second growth jungle of the region. It was 

 not obtained in the heavy forest. 



Specimens examined. — Total number, 23, from the following 

 localities in the Canal Zone: Tabernilla (type locality), 15 ; Gatun, 8. 



