1887.] 



Fig. IG. Thuricolopsis innixa. 



17. Thuricolopsis Kellicottiana. 



18. Platycola coelocbila. 



19. Lagenophrya patina. 



20. Histrio erethesticus. 



21. Solonophora odontopliora. 



22. Acineta bifaria. 



255 



[Scott and Osborn. 



Fig. 23. A. bifaria. Reproductive 

 fission. 



24. A. bifaria. Embryo. 



25, 26. Acineta macrocaulis. 

 Pedicle omitted. 



27. Acineta acuminata. 



Preliminary Report on the Vertebrate Fossils of the Uinta Formation, 

 collected by the Princeton Expedition of 1886. By W. B. Scott and Henry 

 F. Osborn. 



{Bead before the American Philosophical Society, Sept. 2, 1887.) 



The Uinta formation, which was first identified by Prof. Marsh, is one 

 of great interest, as it is just intermediate between the Bridger and the 

 White River groups. It has as yet been comparatively little explored, and 

 much r&mains to be done, but enough is now known to render possible 

 some account of this most important intermediate fauna. 



Crocodilus, sp. indet. 

 Trionyx, sp. indet. 



Hyopsodus gracilis Marsh. 



Mesonyx uintensis Scott. 



REPTILIA. 



MAMMALIA. 



Lemukoidea. 



Creodonta. 



Carnivora. 



Amphicyon (?) vulpinum, sp. nov. — The probable existence of this 

 genus in the Uinta beds is indicated bj-- a lower premolar and lower sec- 

 torial molar. The premolar, probably the third, consists of a high, acute 

 and compressed cone, with rudimentary posterior heel ; a cingulum runs 

 entirely around the crown, and is most conspicuous on the anterior sur- 

 face. This tooth differs from the premolars of most of the European 

 species of Ampldcyon in the fact that the main cusp has no accessory 

 tubercles developed upon it. The sectorial molar is canine in character ; 

 the blade consists of three cusps, of which the external is the larger, and 

 the anterior is very low ; the sectorial blade is therefore much less devel- 

 oped than in Cynodietis, and hardly more than in Miacis ; the heel is low 

 and small and not very distinctly basin-shaped. These teeth are insuffi- 



