2 88 Lloyd's natural history. 



VIII. GENUS POGONODON. 

 Pogonodon, Cope, Amer. Naturalist, vol. xiv. p. 843 (1880). 

 This genus is characterised by the great depth of the flange- 

 like expansion of the lower jaw, and its remarkably broad 

 anterior surface, coupled with the presence of three pairs of 

 lower pre-molars, and the absence of the small last molar. 

 The two known species, P. platycopis and P. brachyops, come 

 from the Upper Miocene strata of the John Day River, Oregon. 

 As they were both of large size, and furnished with long tusks, 

 they would appear to have been the most powerful beasts of 

 prey that flourished in their epoch. 



IX. GENUS AKCILELURUS. 

 Archtzlunis, Cope, Amer. Naturalist, vol.xiii. p. 798, a (1879); 



vol. xiv. p. 841 (18S0). 

 Characterised by the remarkably short muzzle of the skull, 

 which descends abruptly from the forehead, this North Ameri- 

 can genus differs from all the Cats hitherto noticed in possess- 

 ing four pairs of pre-molar teeth in the upper jaw, there being 

 also a small second lower molar. The lower carnassial tooth 

 has no inner cusp, and only a very small posterior heel. It is 

 represented only in the Upper Miocene of the John Day River by 

 A. debilis, a species of the approximate dimensions of a Leopard. 



X. GENUS IIOPLOPIIONEUS. 

 Hoplophoneiis, Cope, Rep. U.S. Geol. Surv. for 1873, p. 509, 



(1874) ; id., Amer. Naturalist, vol. xiv. p. 849 (1880). 

 Although the skull is very similar to that of Nimravus, this 

 genus differs from all the preceding members of the group in 

 the reduction in the number of the teeth, which are numeri- 

 cally the same as in Eusmilus and the True Cats ; that is to 

 say, there is no secoiid molar in the lower jaw behind the car- 

 nassial tooth, while there are only two pairs of pre-molars in 

 the same jaw, and either two or three pairs of upper pre-molar 

 teeth. In this respect, therefore, the genus forms a connect- 



