100 Mr. E. D. Cope on the 



which define the divisions which are regarded as genera by 

 naturalists. It is not unlikely that the typical species has 

 been heretofore estimated as a variety of Cam's familiaris ; 

 but it exhibits two trenchant generic dental characters not 

 found in Cants, and three unique specific characters in the 

 teeth, besides two characters of the cranium found in but one 

 or two of the subspecies of Cam's familiaris. 



The generic characters alluded to are (1) the absence of 

 the second inferior tubercular molar, and (2) the absence of 

 the internal tubercle of the inferior sectorial. The absence of 

 the second inferior tubercular is evidently not one of those 

 abnormal cases which occur in various species of Cam's from 

 time to time ; for the first tubercular molar is smaller than in 

 any known species of Cam's, and has but one root, a character 

 which some persons might regard as being the third of the 

 generic category. The premolars are 4 — 4, and of the usual 

 form ; the first in both jaws is one-rooted. 



It is uncertain whether any species of this genus exists in 

 the wild state. Should such not be the case, we can only 

 predicate the former existence of such a one entirely different 

 from the Cams familiaris, and which has given origin to the 

 existing one below described. 



Synagodus mansuetus, sp. now 



Two crania represent this species in the Museum of the 

 Academy of Natural Sciences. They agree in all essential 

 particulars. The incisor and premolar teeth present no pecu- 

 liarities (the latter are without marginal lobes) ; and the 

 superior sectorial is normal. The first tubercular has less 

 transverse extent than in the Canidas generally ; and its 

 median crest and inner cingulum are confounded, a character 

 which I have not found in any of the other species accessible. 

 Thus the crown of this tooth consists of an external pair of 

 tubercles, a basin, and a stout inner marginal prominence. 

 The second tuberculars are abnormally small in one specimen ; 

 and in the other they are wanting. The 3rd and 4th inferior 

 premolars have marginal posterior lobes. The inferior secto- 

 rial, as already stated, has no inner tubercle ; its heel is 

 peculiar in the great elevation and submedian position of one 

 of its borders, approaching Temnocyon in this respect ; the 

 other edge, however, is distinct, thus forming an unsym- 

 metrical basin. The first inferior tubercular is small, one- 

 rooted ; and the crown is subround, and with a single median 

 tubercle. In the other usual species of Canis, Vulpes, and 

 of many other genera of the family this tooth is elongate, 

 two-rooted, and supports at least two tubercles. 



