324 0. G. Alarsh— Description of new fossil Serpents ■ 



writer, at Grizzly Buttes, near Fort Bridger, Wyoming Territory. 

 The geological horizon is probably Eocene.* 



i species, which was nearly the same in length as the pre- 



ceding, although apparently much more slender 

 all from the dorsal reg" 



nay readily be clistmguis 

 from the corresponding vertebrae of B. occidentalis, by the 



vertebrae, all from the dorsal region, and representing 

 more individuals. They may readily be distinguished 



portionally more elongated centrum ; by the i 

 inclined cup; by the more expanded anterior zygapophyses ; 

 by the diapophyses, which do not extend below the inferior 

 surface of the centrum ; and by the hypapophysial ridge, which 

 is more obtuse, and in its anterior portion expands rapidly until 

 it disappears in the margin of the cup. 



The largest vertebra of this series has the following dimen- 



Length of centrum from edge of cup to convexity of ball, 4-25 lines. 



Transverse diameter of cup, 2'50 " 



Vertical diameter of cup, 2"40 " 



Vertical diameter of ball, 2-35 " 



Width of neural canal in front, 1''75 " 



The specimens on which this species is based were discovered 

 by the writer, near Eort Bridger, in the same formation as the 

 remains above described. 



Boavus brevis, sp. nov. 



The serpents representing this species were considerably 

 smaller than those described above, and evidently much shorter 

 in proportion to their bulk, being probably not more thaii four 

 or five feet in length. The only remains obtained consist ot 

 three dorsal vertebrae, all in good preservation, and evidently 

 belonging to two different individuals. These vertebrae have 

 the centrum unusually short, its extent measured on the inferior 

 surface scarcely exceeding ' the transverse diameter of the 

 zygosphene. The neural arch is low, and bears on its posterior 

 two-thirds the neural spine, which is quite short, and truncatea 

 The zygosphene is less massive than in the preceding species, ana 

 has a slight median swelling on the anterior margin of its bas. 



The dimensions of the most perfect of these vertebrae are as 

 follows : — 

 Length of centrum from edge of cup to convexity of ball, 2-20 Unea. 



Transverse diameter of cup, ^'^ « 



Vertical diameter of cup, ^'^^ u 



Transverse diameter of zygosphene at base, ^'f ,. 



Distance from top of zygosphene to lower margin of cup, 2-80 



Width of neural canal fn front, - - - - I'^J . 



Height of neural canal in front, *^" 



* This Journal, III, vol. i, p. 192, March, 1871. 



