:notes on a newly mounted skeleton of MERY- 

 coidodon," a fossil mammal. 



By Charles W. Gilmore, 



Of tlie Department of Geology. 



During 1897, while engaged in field work for the U. S. Geological 

 Survey, Mr. N. H. Darton collected from the Oligocene deposits of 

 South Dakota a ver}- complete skeleton of the small Oreodont, Mery- 

 coidodon gracilis. 



The portions found consist of a poorly preserved skull and jaws; the 

 vertebral column (articulated) from the atlas to the fourth caudal, one 

 median caudal, twelve ribs of the right side and half of those of the 

 left, three segments of the anterior portion of the sternum; both 

 femora, both tiba?, right patella, articular portions of both scapulae, 

 both humeri (the left one lacking the distal end), proximal ends of 

 both ulna?, both radii (one lacking the distal portion); left scaphoid, 

 lunar, and unciform; second, third, and fourth (latter lacking the dis- 

 tal end) metacarpals; several phalanges, including one ungual of the 

 same foot; astragalus and calcaneum of the right hind foot; a portion 

 of the h3^oid arch. 



This specimen (Cat. No. 2455), which was freed from the matrix and 

 mounted by the writer, has recentl}^ been placed on exhibition in the 

 U. S. National Museum. (See Plate XII.) So far as the writer is 

 aware, it is the first example of this particular species to be thus 

 exhibited. 



The poorly preserved skull and jaws of Cat. No. 2455 have been 

 replaced by the homologous parts of a more complete but somewhat 

 smaller individual. Cat. No. 136, U.S.N.M. The latter elements are of 

 peculiar interest as having been the subjects of study and illustration by 

 Dr. Joseph Leid}^ as early as 1869 in his Extinct Mammalian Fauna of 

 Dakota and Nebraska.* The remainder of the skeleton pertains to 



« Commonly known as Oreodon. See Hay, Bull. No. 179, U. S. Geol. Surv., p. 665. 

 6 Jour, of the Acad, of Nat. Sci. (2), VII, 1869, p. 94, pi. vi, %,«. 2 and 3. 



Proceedings U. S National Museum, Vol. XXXI— No. 1492. 

 Proc. N. M. vol. xxxi— 06 34 _ 513 



