1881.] ■l^*' [Cope. 



Size as last ; last molar shorter than second .H. miticulus. 



Length of true molars M. .0115 ; last molar elongate H. vicarius. 



H. lemoinianus and H. miticulus have not been found out of the localities 

 where they were discovered, while the other two species are distributed 

 through most of the Eocene horizons, and have been found in many 

 localities. Of the H. lemoinianus Mr. Wortman found nine more or less 

 fragmentary mandibles. 



Dedicated to my friend, Dr. Victor Lemoine of Reims, well-known for 

 his brilliant discoveries in the vertebrate, paleontology of the Lower Eo- 

 cene beds near that city. 



Hyopsodus patjlus Leidy. 



Thirty-eight more or less broken mandibular rami. 



Hyopsodus vicarius Cope. 



Eleven mandibular rami. A few specimens are intermediate between 

 this species and the last in dimensions, the inferior true molars measuring 

 M. .0120 and .0125 in length. 



Pantolestes chacensis Cope. 



Four mandibular rami. This species has the fourth premolar more 

 robust and less trenchant than in P. secans, and shorter than the last true 

 molar. In P. secans it is longer than the last true molar. 



Pantolestes metsiacus sp. nov. 



A small species of the size of the P. longicaudus, and distinguished by 

 several peculiarities of dentition. The two cusps composing the anterior 

 internal lobe of the molars are quite distinct but appressed. Each one is 

 connected with the external anterior lobe by a transverse crest as is seen 

 in Esthonyx, and these enclose between them a fossa. This fossa is closed 

 internally by the appression of the anterior inner cusps. The fourth pre- 

 molar is not so large as in P. secans, but resembles in proportions that of 

 P. chacensis. It differs from that of P. longicaudus in its very short heel 

 and its large anterior basal tubercle. The latter is double, consisting of 

 two small cusps, one within and anterior to the other. The posterior heel 

 is distinct on both sides of the ridge that marks the median line. The 

 posterior external lobe is V-shaped, and the posterior inner is a small cone. 

 Between the two is a minute median tubercle. The posterior tubercles are 

 not so elevated as in the species of Hyopsodus. A weak external cingulum ; 

 enamel smooth. 



Measurements. M. 



Length P-m. IV, with M. I, and II ; (No. 1) 0140 



" P-m. IV 0048 



" M. II 004j 



