No. 2391. DESCRIPTIONS OF PLEISTOCENE VERTEBRATA— HAY. 627 



Family SCIURIDAE. 



MAKMOTA ARIZONAE, new species. 



Plate 123, figs. 6-8. 



Type specimen. — The front two-thirds of a skull (Cat. No. 10181). 



Type locality. — Coconino Forest region, Arizona. 



Type formation. — Early Pleistocene. 



Diagnosis. — Belonging near to or within the jlaviventer group of 

 the genus. Snout narrower and more rounded than in M.f. obscura. 

 Nasal processes of premaxillae broader than in the just mentioned 

 subspecies. Incisors obsoletely striated. 



A species of marmot belonging apparently to the group of M. 

 jlaviventer is represented by the anterior part of the skull of one 

 individual and two molar teeth of another. On comparison of the 

 skull with that of a specimen of M. jlaviventer obscura — a female 

 from San Miguel county, New Mexico — differences appear which, on 

 the discovery of additional materials, may prove to be of specific or of 

 only subspecific value. At the present day no species of marmot is 

 known to live within the territory of Arizona; and New Mexico har- 

 bors only in its northern part the subspecies named above — M. 

 jlaviventer obscura. 



Figures 6-8 of plate 123 present views of the specimen on which 

 the new species is based. The incisor teeth are broken off at the 

 bone. On the right side, three molars, little worn, are present; on 

 the left side, only one. The nasal bones and the zygomatic arches 

 are missing. The distance from the rear of the last molar to the 

 front of the premaxillae is 47 mm. In the recent skull used for 

 comparison this distance is 46 mm. The nasal process of each 

 premaxilla is nearly as wide as the space occupied by both of the 

 nasals. The width of the frontals at the front of the orbits is some- 

 what less than in the recent skull. Examined from below, the 

 snout is narrower in the fossil. The width at the maxillo-premaxillary 

 suture is 19 mm.; in the recent skull, 20 mm. The palate behind 

 the incisors is more rounded from side to side. In the recent skull 

 a ridge running back on each side from the incisor gives an effect of 

 squareness to this region. The processes on the maxillae just in 

 front of the rows of teeth appear to be unusually strongly developed 

 in M. f. obscura. They are much less prominent in the fossil. No 

 differences are observed in the rows of teeth or of the individual 

 molariform teeth. The incisors of M. f. obscura are very distinctly 

 striated; in the fossil they are nearly smooth. 



CITELLUS TUITUS, new species. 



Plate 120, figa. 5-6. 

 Type specimen. — The anterior half of a skull, with incisors and 

 all the upper teeth except the third premolars (Cat. No. 14353 of 

 the Amer. Mus. of Nat. History). 



