150 PROCEEDmO^ OF THE NATIONAL MUSEUM. vol.49. 



furred; claws short, sharply pointed; fingers and toes partially 

 webbed; limbs short. 



Skull short, rounded, and highly arched; rostrum short and broad; 

 braincase large, sharply constricted in the postorbital region (in fully 

 adult skulls the postorbital constriction is greater than interorbital 

 constriction); postorbital processes well developed from frontals, 

 only shghtly so from zygomata; sagittal crest usually developed on 

 forward half of braincase. Palate flat, short, and extending poste- 

 riorly only short distance beyond plane of maxillary tuberosities; 

 audita! bullae much flattened, about equally inflated anteriorly and 

 posteriorly. Mandible heavy, the ascending ramus high, straight, 

 and little produced backward. 



• 3 1 3 2 

 Dental formulae '• 'i ;^ c - pm - m - = 36. 



Teeth, excepting m^, larger than in Bassaricyon, flatter, lower 

 crowned, and still less tuberculated; entire row interrupted only by 

 very short incisor-canine diastema. Incisors heavy, broad; the 

 outer pair proportionately much larger and deeply emarginate over 

 the posterior cingulum fold; lower incisors with chisel-shaped 

 crowns, the central pair small. Canines large, much flattened, and 

 emarginate on inner surfaces, and deeply grooved on outer sides; 

 nearly straight. Premolars all large, the fu"st two {pm- and pm^) 

 simple, with blade-like, crested crowns; pm^ very broad, a long 

 lateral shelf to the single internal, low and rounded cusp. First 

 upper molar about twice the size of second, subquadrate, and almost 

 flat except for outer raised rim; m^ and both lower molars slightly 

 sculptured and virtually without tubercles. (Plate 39.) 



EXPLANATION OF PLATES. 



Plate 38. 



Skulls of Nasuella and Nasua (natural size). 



Fig. 1. Nasuella olivacea meridensis, Cat. No. 143658, U.S.N.M. 

 2. Nasua nasua, Cat. No. 61489, U.S.N.M. 



Plate 39. 



Right upper tooth-rows of Procyonidse. 



(To facilitate comparison of the important features of the crown patterns, these tooth- 

 rows are figured at same size, based on length of the three large molariform teeth.) 



Fig. 1. Ailurus, Cat. No. 12420, Acad. Sci., Philadelphia. 



2. Euprocyon, Cat. No. 172987, U.S.N.M. 



3. Proajon, Cat. No. 6025, U.S.N.M. 



4. A^aswa, Cat. No. 61489, U.S.N.M. 



5. Nasuella, Cat. No. 143658, U.S.N.M. 



6. Bassaricyon, Cat. No. 171138, U.S.N.M. 



7. Potos, Cat. No. 74684, U.S.N.M 



