1870.] NATURAL SCIENCES OF PHILADELPHIA. 189 



the direct line of numerical succession of parts already repre- 

 sented by the genera of Ganidse, and of all digitigrade Carnivora. 

 This, as already stated, consists in the reduction in the number of 

 the teeth and their tubercles, forming a series which, commencing 

 with the generalized extinct type Amphicyon, approaches more 

 and more nearly to the Felidse. In the inferior sectorial, the 

 genus Bysodus approaches nearest of all Ganidse to some of the 

 earliest genera of cats, as Nojylophoneus (although easily distin- 

 guishable), while in the reduction of its premolars it approaches 

 the modern forms of that family. In the early shedding of the 

 incisors it reaches a condition not found in any carnivora, but one 

 which marks the extreme of development of the ungulate mammals 

 in various lines; e. g., Buminantia, Omnivora, and Amblypoda. 



Dysodus pravus, sp. nov. 



This species, which is known as the Japanese sleeve dog, is re- 

 presented in the Museum of the Academy of Natural Sciences by a 

 complete skeleton, with the crania of two other individuals. These 

 all belong to adult animals of a single litter, which were born in 

 the United States. The parents of these clogs were procured in 

 Japan by Dr. W. S. TV. Ruschenberger, U. S. N., now President 

 of the Academy. Other specimens have been brought to the 

 United States by officers of the navy. Dr. J. E. Gray figures a 

 skull of the same dog in the Proceedings of the Zoological Society 

 of London for 1867. 



The crania in the Academy's collection are almost exactly alike, 

 and resemble the one figured by Dr. Gray so far as can be discov- 

 ered. But Dr. Gray's specimen was probably young, as the inci- 

 sor teeth and a premolar in each jaw have not yet been shed, and 

 there are some cranial fontanelles still remaining. 



The characters displayed by the skulls are as follows: The muz- 

 zle is excessively abbreviated, and the forehead very convex. The 

 brain-case is almost globular, and the zygomata proportionably 

 prominent. The superior marginal ridge of the temporal fossa is 

 prominent, and those of opposite sides are well separated as far 

 as the posterior parietal region. Here the}' approach each other 

 abruptly, forming a wide sagittal crest. The muscular insertions 

 and other osseous ridges of the supra, ex- and basi-occipital re- 

 gions are strongly marked. The postorbital process is prominent 

 and decurved. The vertical sinus of the superior border of the 



