105 [Wyman. 



March 15, 1865. 



The President in the chaii*. 



Thirty-five members present. 



Prof. Jeffries Wyman exhibited the fossil bones recently 

 collected near Riobamba, South America, by Dr. C. F. 

 Winslow, and presented by him to the Society ; giving an 

 enumeration of them with some brief observations on the 

 most interesting forms. 



BONES OF A HORSE. 



1 . A fragment of the left temporal bone, including a part of the 

 squamous portion, about two-thirds of the glenoid fossa, and the pos- 

 terior glenoid process. 



2. A fragment of the right lower jaw, comprising the last two mo- 

 lars with their alveoli and a small portion of the base of the coronoid 

 process. 



3. A fragment of the " angle " of the same part and probably from 

 the same individual as the preceding. 



4. The third molar tooth from the right upper jaw. 



5. The atlas nearly entire. 



6. The second phalanx of the fore-foot. 



The above remains indicate the existence of a species of horse some- 

 what smaller than the horses of the present time. This is evident, as is 

 seen in the following tables, from a comparison of the corresponding 

 parts of the extinct and fossil species. 



Transverse diameter of 3d upper molar 

 Longitudinal " " " « " 

 Length of 5 th lower molar 

 " " 6th " " . 



Greatest diameter from side to side . 



" " " before backwards 



Transverse diameter across posterior 



articular surfaces . . . , 3.28 3.53 



Transverse diameter across anterior 



articular surfaces . . . . 2.13 3.54 



Greatest thickness from dorsal to ventral 



surface , 2.76 3.16 



This bone is broader and more depressed in the fossil than in the 



