On the Tseniodonta, a new group of Eocene Mammalia. — Prof. 

 Cope described the characters of some mammalia from the Eocene 

 of New Mexico, obtained by him during the Wheeler expedition 

 of 1874, which he regarded as allied to the Insectivora. The feet 

 are armed with compressed claws. The dental characters are seen 

 first in the supposed superior incisors. Unfortunately, they have 

 not yet been found in place in the cranium, but their association 

 with a rodent type of inferior incisors, which have been found in 

 place in the mandible, confines us to the alternative choice between 

 superior incisors and- canines. From the small size, or absence, of 

 inferior canines, a similar character may be inferred for the supe- 

 rior canines. 



These superior incisors present two bands of enamel, an anterior 

 and a posterior. They are compressed in form, the sides pre- 

 senting a surface of dentine or cementum. Attrition produces a 

 truncate or slightly concave extremity. The inferior incisors are 

 rodent-like. 



Two families represented this suborder in the Eocene period in 

 New Mexico. The first, or Ectoganid.se, possesses molar teeth 

 with several roots ; in the Galamodontidse, each molar has a 

 simple conic fang. But one genus of each family is known. In 

 both the enamel of the molars is principally a band on the outer 

 side of the crown ; the deficiency is supplied in Calamodon by a 

 deposit of cementum, which invests the molar and superior incisor 

 teeth, covering the crowns, excepting where the enamel bands are 

 present. The latter investment is so much thinner, that the 

 cementum forms a raised border all round at the point of junction 

 of the two substances. The general structure of Calamodon 

 affords some points of approximation to the Edentata, which 

 indicate that the Tseniodonta partially fill the interval between 

 that order and the Insectivora, presented by the existing fauna. 



Prof. Cope also pointed out the close resemblance between the 

 mandibular dentition of the cotemporary Eocene genus Esthonyx, 

 and the existing Erinaceus, and stated that that of Anchippodus 

 and allies chiefly differs from the latter in the persistent growth of 

 the incisor teeth. 



Philadelphia, April 18, 1876. 



