NEW CALIFORNIA WOOD-RAT. 1 55 



sciintil}'^ clothed with appressed whitish hairs. In color- 

 ation this species differs from A\ mcxicana in having the 

 purely white patches on the under side larger, the dusky 

 element in the dorsal coloration more extensive, and the 

 lighter element light yellow or buff, instead of deep ful- 

 vous or tawny. 



Cranial characters. — In its cranial characters this spe- 

 cies very closely resembles N. mexicana, with which it 

 agrees in the broadly-rounded temporal region, the weak- 

 ly-marked temporal ridges, the short, deep snout, with 

 the nasal bones anteriorly produced and overlapping, and 

 the very small auditory bullae. The two agree also in 

 shape of mandible, having a very slender, backwardly- 

 curved coronoid process, and a narrow, acute-angled 

 postcoronoid notch. 



They differ in the following respects : 

 In californica the nasal processes of premaxillaries ex- 

 tend posteriorly to well be3-ond the nasal bones, while in 

 mexicana they terminate evenly, or nearly so. 



In californica the interparietal is longer (antero- 

 posteriorly) in proportion to its width, with a strong 

 posterior angle. In mexicaria the posterior edge is evenly 

 rounded, or nearly straight, without well-defined angle. 

 In californica the incisive foramina are short, 8.5 mm. 

 in length. In mexicana they are unusually long, from lo 

 mm. to II mm. in specimens of equal size with the 

 former. 



Cranial Measurements. 

 Skull of type No. 335. 



Basilar length of Hensel, 35.5 mm. 



Greatest zygomatic breadth, 23. mm. 



Least interorbital width, 5.5 mm. 



Length of nasals, 16.3 mm. 



Distance from incisors to incisive foramen, 3.8 mm. 



