Tertiary Vertebrata of the West. 



415 



round it combines to suggest the characters of an Edentate. So that 

 Calamodon is thought to furnish a hint of the relationship of the 

 Edentata to other Mammals. Tceniolahis is a genus of allied character, 

 founded on a single tooth. The Tillodonta is a suborder with 

 rodent-like incisor teeth ; and this character distinguishes the group 

 from the Insectivora, to which the molar teeth approximate. There 

 are three genera in this suborder. Psittacotherium has six inferior 

 molars with cross crests, which with wear assume the form of the 

 letter B, with the convexities turned forward. The incisor teeth are 

 powerful and adapted for breaking nuts or cutting fruits. Two 

 species are known. The other genera of this group have no repre- 

 sentatives in the Wasatch and Bridger faunas. The Insectivora, 

 which alone survive at the present day of all the Bunotheria, 

 are well represented by the genera Conorycthes and Esthonyx. 

 Esthonyx approximates to the Tillodonta in having the enamel 

 of the incisors restricted in the lower jaw to the front of the tooth. 

 The lower molars closely resemble those of the Hedgehogs, but 

 several affinities are seen with Lemurs like Chiromys, and with the 

 genus Pelycodns. Conorycthes has two inferior incisors, and is repre- 

 sented by several species. Esthonyx has three inferior incisors. It is 



Upper 



Kit 







Lower 





Upper 



Lower 



Esthonyx Burmeisteri. 



remarkable for having the scaphoid and lunar bones separate, which 

 is not the case with existing Hedgehogs. Four species are known. 

 Another Bunotheroid suborder is named Mesodonta, — animals 

 characterized by approaching the Quadrumana in proportions, 

 but the rami of the mandible are separate, so that they also 

 approximate towards Lemurs. Several allied forms occur in the 

 Eocene of France, and it gradually became manifest that these 



