T^NIODONTA. 187 



been Bunodonts with pentadactyle plantigrade feet. We may anticipate the 

 discovery of such a genus, and believe that it will not be widely removed 

 from the Eocene Hyoj^sodus, or perhaps Achcenodon. But it will be more 

 than this: it cannot be far removed from the primitive Carnivora and the 

 primitive Quadrumana. The Carnivora are all modified Bunodonts, and the 

 lower forms (Ursus, Procyon, etc.) are pentadactyle and plantigrade; as 

 to the Quadrumana, man himself is a pentadactyle plantigrade Bunodont* 



Such a hypothetical type might be expressed by the name Bunotheriidce, 

 with the expectation that it will present subordinate variations in premolar, 

 canine, and incisor teeth. The premolars might be expected to differ in the 

 degree of development of the internal lobes, the canine in its proportions, 

 and the incisors in their number." 



The history of discovery of the Eocene forms of this order is briefly 

 told. Professors Leidy, Marsh, and myself had described Creodonta as 

 Carnivora, until I pointed out, in some remarks before the Philadelphia 

 Academy (published December 22, 1875) their true relations. The first 

 species of Tillodonta was described by Leidy from an inferior molar from 

 New Jersey, in 1868. Dr. Leidy next described the dentition of the mandi- 

 ble of the same genus from Wyoming. Subsequently, Marsh described the 

 superior molars of an allied genus, from Wyoming. In 1874, the writer 

 described the dentition of the Tceniodonta from specimens collected by Lieu- 

 tenant Wheeler's Survey in New Mexico. In March, 1875, Marsh proposed 

 the Tillodonta as an order of Mammals, giving its dental characters, and 

 stating the brain was small. In December, 1875, in his remarks on Creo- 

 donta, I referred this group to the Insectivora as a suborder. In March, 

 1876, Professor Marsh gave a full description of the cranial characters of 

 the genus Tillotherium, describing the characters of the brain from a cast of 

 the cranial cavity. In the same month of 1876 the writer characterized the 

 suborder Tceniodonta, referring to it the genera JEctoganus and Calamodon. 



T^NIODONTA. 



The Tceniodonta agree with the Tillodonta in the possession of a pair of 

 inferior incisors of rodent character, but it adds several remarkable pecu- 



*0n the Homologies and Origin of the Types of Molar Teeth of Mammalia Educabilia, Journal 

 Academy Philadelphia, 1S74, p. 20. 



