EODENTIA. 183 



M. 



Length of head of astragalus 0055 



Diameters of navicular face of astragalus )^ nnon 



( transverse OUoO 



Depth of heel of calcancum at base 0080 



Depth of cuboid facet of calcancum at base 0057 



Width at susterotaculum 0132 



Plesiaectomys leptodus Cope. 



Faraniys leptodus Cope, Paleontological' Bulletin, No. 12, \i. 3, March 8, 1873. 



Plate xxiv, fig. 1. 



Established on a right mandibular ramus with all the teeth preserved. It 

 indicates an animal of about the size of the P. delicatus Leidy, but with 

 smaller incisors, which have little more than half the diameter of the same 

 tooth in those species. The molars have two anterior separate, and three 

 posterior contiguous cones, the median smallest, the anterior and posterior 

 of both sides separated by a deep excavation. The anterior tooth is pecu- 

 liar in its greater compression. The posterior tubercles are not separated, 

 and the anterior inner is situate behind the outer, and is connected with the 

 posterior inner by a concave ridge. 



Measurements. 



If. 



Length molar series 0221 



Length M. IV 0060 



Width M. IV 0055 



Length M. I , 0060 



Width M. I 0048 



Diameter lower incisor, transverse 0024 



Diameter lower incisor, anteroposterior 0038 



From the South Bitter Creek, Wyoming, from the Washakie Basin. 

 Plesiaectomys hians Cope. 



Pseudotomus hians Cope, Paleontological Bulletin No. 2, p. 2, 1672. Annual Report U. S. Geol. Sury. 

 Terrs., 1872, p. 611. 



Plate xxiv, figs. 3-5. 



This species was established on a nearly complete cranium, from which 

 some parts of the walls are broken, and only the anterior portion of the 

 mandible remains. It belonged to an old individual which had lost its molar 

 teeth, and whose inferior incisors are very much worn. 



The cranium is of depressed form, and with considerably expanded 



