IGO ON THE EXTINCT MAMMALIA OF 



PROTOMERYX. 

 Protomertx Halli. 



A fossil obtained by Dr. Harden at Bear Creek, a tributary of White River, in the 

 Mauvaises Terres, indicates an extinct animal, apparently a member of the Camel 

 family, and different from any other described. The fossil belongs to the miocene 

 formation, represented by bed D of Dr. Hayden's section, as indicated on pages 

 17, 21. 



The specimen, represented in figures 8, 9, plate XV, consists of the fore part of the 

 left side of a lower jaw, with the greater part of the symphysis, three incisive alveoli, 

 the canine tooth, part of a caniniform premolar, and two other premolars. 



In comparison with the corresponding portion of the jaw of the Camel or Lama, it 

 is of relatively greater depth, less convex externally, and has the symphysis shorter 

 and more oblique. 



The alveolar portion of the jaw, sustaining the back premolars, is vertical and flat, 

 but below, the bone is more convex. The symphysis forms an angle of about 35°, and 

 when entire has approximated an inch and a half in length. It terminates posteri- 

 orly below and back of the middle of the hiatus behind the caniniform premolar. 



The mental foramen is situated about midway below the middle of the hiatus just 

 mentioned. A minute foramen, of the same character as the former, is situated 

 below the back part of the canine tooth. 



The hiatus between the caniniform premolar and the other premolars is a concave 

 space about four and a half lines wide. That between the canine tooth and the 

 caniniform premolar is scarcely two lines, and a third, hardly a line in extent, inter- 

 venes between the canine tooth and lateral incisor. 



The depth of the jaw below the middle of the second premolar is ten lines; below 

 the hiatus in advance, eight lines and a quarter. 



Of the three incisive alveoli, the two lateral contain portions of the fangs. 



The canine tooth, figures 8, 9, h, holds nearly the same relative position as in the 

 Camel. It curves upward, forward, and slightly outward. Its fang is robust and 

 somewhat gibbous. The crown is much worn, and appears to have been laterally 

 compressed conical. 



The caniniform premolar, figures 8, 9, c, likewise appears to have held the same 

 relative position as in the Camel. Its crown is broken away in the specimen. 



The tivo succeeding premolars, figures 8, 9, d, e, are nearly alike in size and form, 

 the first being rather smaller and less well-developed. The crowns are twice the 

 width of the height, are laterally compressed conoidal, and feebly trilobate. The 

 second is slightly worn ; the third considerably. 



The second premolar is 4 lines wide and two lines high, which was nearly its 



