228 



If the upper sectorial molar of Fells atrox had the same proportionate size 

 to the lower one as in the Bengal tiger and other feline animals, it measured 

 nearly an inch and three-fourths in breadth. That of the Loup Fork fossil 

 is a little over an inch and a quarter in breadth. From the difference iu size 

 thus indicated between the sectorial molar of the Loup Fork fossil and that of 

 the previously described largest American cats, recent and extinct, we -may 

 fairly regard the specimen as characteristic of another species, for which the 

 'name heading this chapter has been proposed. 



Comparative measurements of the upper sectorial molar are as follows — 

 those from Fells atrox being estimated, and that from the jaguar being taken 

 from Plate XIV of De Biainville's Osteographie: 



Another Specimen, represented in Fig. 18, Plate VII, consisting of a frag- 

 ment of a premaxillary retaining the second incisor, the first alveolus, and part 

 of the last one, agrees in size and other characters with the corresponding 

 part in the Bengal tiger. 



The remaining specimens are fragments of an upper last premolar and of a 

 canine from the same individual. 



A specimen, represented in Fig. 24, Plate XX, found by Professor Hayden 

 on the Niobrara River, but not in proximity with the preceding, consists of 

 the distal extremity of a humerus, probably of the same animal. It has 

 about the same size, proportions, and form as in the corresponding part of 

 the arm-bone of the Bengal tiger. Its diameter at the supracondyles is 3| 

 inches ; the breadth of the articular surface in front is 2| inches. The hole 

 for the brachial blood-vessels and accompanying nerve is quite evident, though 

 the bony bridge defining it is broken. 



Felis imperialis. 



Among a collection of fossils belonging to the cabinet of Wabash College, 

 Crawfordsville, Indiana, purchased from Dr. Lorenzo Y. Yates, of Centreville, 

 Alameda County, California, there are several which were kindly loaned to 



