446 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.47. 



15.4). Skull: Condylobasal length, 25.9 (24.8-27.3); zygomatic 

 breadth, 15.1 (14.1-16.1); interorbital breadth, 5.0 (4.7-5.3) ; breadth 

 of bramcase, 12.7 (12.3-13.1); length of nasals, 10.9 (10.3-11.4); 

 length of mandible, 15.4 (14.8-15.9); maxillary tooth row, 4.6 

 (4.4-4.8). For detailed measurements of specimens, see page 476. 



Type-specimen. — No. 186477, United States National Museum. 

 Skin and skuU of adult male (teeth httle worn), in full whiter pelage. 

 Collected December 22, 1888, by Vernon Bailey. Original number 

 458. Merriam collection number fm. The colors, especially of 

 tail, feet, and ears, have been destroyed by painting with corrosive 

 subhmate and exposing to fumes of carbon bisulphide, which has 

 turned them a dark plumbeous color. 



Remarks. — This form intergrades with ruidosse wherever the 

 ranges meet. Specimens from New Mexico average shghtly larger 

 and have slightly longer ears than skins from Utah and Colorado, 

 but the coloration is remarkably uniform over the mapped range of 

 the subspecies. 



The abundant material now in the collection makes it clear that 

 0. Z. melanophrys and Onychomys melanopJirys pallescens Merriam 

 are indistinguishable. The type of pallescens, from Moki Pueblos, 

 northeastern Arizona, is in the faded spring pelage. The type and 

 topotypes of melanophrys can be almost exactly matched in color 

 by numerous specimens from Wingate, and even as far east as the 

 Sandia Mountains, New Mexico. 



In fresh pelage 0. I. melanoplirys is a handsome mouse, and it 

 differs conspicuously in color from all the other races of leucogaster. 

 It is most hke 0. I. arcticeps from the Great Plains, but is decidedly 

 richer and darker colored. 



Specimens examined. — Total number, 147, from locahties as 

 follows : 



Utah: Bluff City, 2; Hanksville, 1; Kanab, 15, including the 

 type; River View, 1; Thurber, 1. 



Colorado: Antonito, 1; Conejos River, 2; Coventry, 1; Fruita, 

 5; Medano Ranch, 15 miles northeast of Mosca, 3; Naturita, 2. 



Arizona: Flagstaff, 1; Holbrook, 8; Keams Canon, 1; Moa Ave, 

 Painted Desert, 4; Moki Pueblos, 3, including type of "pallescens"; 

 Oraibi, 1; Tuba City, Painted Desert, 1; Walnut, 6; Winslow, 11; 

 Zuni River, 2. 



New Mexico: Acoma, 1; Albiquin, 6; Albuquerque, 1; Carasal, 

 Bernalillo County, 2 (Mus. Comp. ZooL); Chaco Canyon, 2 (Amer. 

 Mus.) ; Chama River, 1 ; Espaiiola, 1 ; Fruitland, 2; Gallina, 1 ; Gallup, 

 13; Jamez, 1; Laguna, 1; La Plata, 1 (Amer. Mus.); Sandia Moun- 

 tains, 3; Santa Fe, 1; Stinking Spring Lake, 4; Tierra Amarillo, 1; 

 Wingate, 32; Zuni River, 1. 



