A. gi 



acilis. 



C. velox. 



. 5 lines. 



5 J lines. 



. ii 



a 



6 " 



. 2 



(I 



2i " 



. 21 



a 



3 "t 



. 3 



a 



3i " 



. U 



a 



11 " 



. 2 



ic 



2i "t 



DAKOTA AND NEBRASKA. 37 



than in the smallest existing species of American Foxes, the Vulpes littoralis of the 

 island of San Miguel, on the coast of California, described by Prof. Baird.* 



The teeth contained in the specimen consist of the sectorial molar and the premolar 

 in advance. They have the same form and constitution, and nearly the same pro- 

 portions as in existing canine animals. 



The measurements of the specimen, in comparison with those of the Swift Fox, are 

 as follows : 



Depth of lower jaw below sectorial molar, 

 Antero-posterior diameter of sectorial molar, 

 Transverse " " " 



Height of sectorial molar, 



Antero-posterior diameter of premolar in advance. 

 Transverse " " " 



Height of premolar, .... 



Dr. Hayden's last collection from the Mauvaises Terres contains several additional 

 fragments of lower jaws, and the greater portion of the facial extremity of a skull of 

 Amphicycon gracilis. 



One of the lower jaw fragments contains the sectorial molar and the succeeding 

 tubercular molars, which, together with the premolar in advance from the specimen 

 first described, are represented in figure 9, plate V. The sectorial molar and the 

 first tubercular molar are like those of the Dog. The second tubercular molar, 

 though small, is not of the simple character of that of the latter, but is inserted by a 

 pair of fangs and has a crown, which in form is the reduced likeness of its fellow in 

 advance. 



The facial portion of a skull represented in figures 6, 7, 8, plate V, resembles in 

 its construction the corresponding part of the skull of the Dog or Fox. The face 

 is relatively shorter, and the molar and canine teeth are closer together. The 

 sagittal crest is linear, and remains undivided to within a few lines of the position of 

 the postorbital processes. A slight depression of the surface exists just in advance of 

 the ant-orbital margin, and a depression also exists over the post-orbital processes. 



The specimen contains on the right side the sectorial molar and the succeeding 

 tubercular molar, which agree in character with those of the Dog. In advance of 

 these teeth are the sockets of all the others, which agree in number with those of the 

 latter animal, 



Measurements of the specimens are as follows : 



* Rep. of Bspl., &c., for a Railroad, vol. viii, p. 143. 



t These measurements estimated, as the teeth are much worn in the specimen. 



