1883.] 5o9 [Cope. 



navicular face is flat, tliat of the cuboid bone is convex vertically, and one- 

 half as long horizontally as the navicular, and only half as deep. These 

 two facets are continuous with the sustentacular below. Interior to 

 all of these, on the internal tuberosity of the head is a sub-round facet look- 

 ing inwards, like that characteristic of the genus Bathmodon, but rela- 

 tively larger. A coatinuous facet is seen on the adjacent edge of the 

 navicular. The use of tliese facets is unknown. 



The brain case indicates small and nearly smooth hemispheres, extend- 

 ing with little contraction into a rather large cerebellum. The olfactory 

 lobes are produced anteriorly at the extremity of a rather long isthmus. 



If we consider the dentition alone, Pantolambda is the ancestor of the 

 Coryphodontida. The history of the feet requires further elucidation. 



The Pantolambda bathmodon is about as large as a sheep. 



From the upper beds of the Puerco. 



MixODECTES PUNGENS, gen. ct sp. nov. » 



Char. Gen. — The position of this genus is uncertain, but may be near to 

 Cynodontomys Cope, which I have provisionally placed among the Pro- 

 siniiae*. It is only known from mandibles, which have presumably the 

 following dental formula. I. ; C. 1 ; P-m. 4 ; M. 3. An uncertainty 

 exists as to the proper names of the anterior teeth, which cannot be de- 

 cided until the discovery of the superior series. For instance the formula 

 may be ; I. 1 ; C. 1 ; P-m. 3. 



The supposed canine is a large tooth, issuing from the ramus at the 

 symphysis like a rodent incisor, and has an oval section, witli long dia- 

 meter parallel to the symphysis. Tlie crown is lost from all the speci- 

 mens. The second tooth is similar in form to the first, but is much 

 smaller. It is situated posterior and external to the first. The next tooth 

 'is still smaller and is one-rooted. The third and fourth premolars have 

 simple conic crowns, and more or less developed heels without cusps. The 

 true molars are in general like those of Pelyeodus ; i. e., with an anterior 

 smaller, and a posterior triangle or V. The supplementary anterior inner 

 cusp is quite small, while the principal anterior inner is elevated. The 

 posterior inner is much more elevated than in the species of Pelycodm. 

 Last inferior molar with a fifth lobe. 



This genus cannot be referred to its place without additional material, 

 but the parts discovered indicate it to be between Pelyeodus and Cynodon- 

 tomys ; either in the Mesodonta or the Prosimke. I may here remark that 

 in defining the latter genus I was in doubt as to the number of the inferior 

 premolars. The discovery of the present genus renders it probable that it 

 has three such teeth, and that the anterior two are each one-rooted. 



C7ut/r. Specif. The mandible of the Mixodeetes pungens is about the size 

 of that of the mink. Its inferior outline is straight to below the second 

 premolar, whence it rises upwards and forwards like that of a rodent. 

 The anterior masseteric ridge is very prominent, but terminates below the 



» Paleontological Bulletin Xo. 31, p. 151. 



