186 TnE WASATCH AND BRIDGER FAUN^. 



Incisors much eularged, growing from persistent pulps, and faced with 



enamel in front only ; therefore scalprifonn Tillodonta. 



Incisors much enlarged growing from persistent pulps, the superior with 



enamel in anterior and posterior bands, and hence truncate Taniodonta. 



The order of JBunotheria with tliese subdivisions, is not more heterogene- 

 ous than that of the Marsupialia, and presents a great similarity in its com- 

 ponent parts. Thus the Creodonta resemble Sarcophaga, the Insectivora the 

 Entomophaga, and the Tillodonta the Bhizophaga. Fhascolamys, the type of 

 the last suborder presents several points of resemblance to the Tillodonta. 



The affinities of the groups here combined under one ordinal caption 

 are very divergent. The order is generalized, and, as such, does not 

 present the peculiar features of the Chiroptera, Modentia, and Edentatu, 

 but is so far negative in its character as to preclude more than subordi- 

 nate subdivision. While the existing division Insectivora maintains the 

 typical characters, the Dermoptera, also existing, are doubtless relics of 

 the group from which the Chiroptera derive their ancestry. The Tillo- 

 donta exhibit some kind of affinity to the Rodents, while the Tceniodonta 

 present us with a point of connection with the Edentata. The discovery 

 of this fact was particularly welcome, as we had not previously had any 

 hint of the relations between that anomalous order and the remainder of the 

 Mammalia. So far the relationships indicated are to smooth-brained 

 (lissencephalous) orders only. The connections with the Gyrencephala (or 

 Educabilia) are quite as close; namely, as already pointed out, through Me-so- 

 donta to the Prosimice and the Quadrumana, and through the Creodonta to the 

 Carnivora. Standing in this structural relation to different existing types, 

 and in an antecedent relation as to time, it is easy to look on the Bunotheria 

 as ancestral to some of them. In the first place, the Insectivora represent 

 them in the existing fauna. The Creodonta are probably the ancestors of 

 the Carnivora, and the Mesodonta of the Prosimi<je. This ancestry is rendered 

 almost certain by the discovery, by Drs. A. Milne Edwards and Grau- 

 didier, of the affinity existing between the Prosimio' and the Carnivora. 



Before the discovery of the species and genera which form the subjects 

 of this report, I wrote as follows: "I trust that I have made it sufficiently 

 obvious that the primitive genera of this division of Mammals must have 



