W. M. Gabb.on the Vegetation of Santo Domingo. 127 
Measurements. 
Length of portion of tibia preserved, 15° lines 
meee 06nd vies in fronts. xcwscashnmbane~ ino ben 
Transverse anterior diameter of inner condyle, yee 
Transverse anterior diameter of outer condyle, --- ---- Se: ee 
This specimen, the only known representative of the species, 
was found by the writer last autumn at Grizzly Buttes, near 
Fort Bridger, Wyoming. 
Yale College, New Haven, June 12th, 1871. 
Art. XVIIL—WNotes on the distribution of the Vegetation of Santo 
Domingo; by W. M. Gass. 
Mucu has been said and written on the singular phenomenon, 
exhibited on a grand scale in our western prairies as we 
South America and elsewhere, of large treeless areas, strongly 
circumscribed, and covered with grass. Innumerable theories 
have been advanced to account for the absence of forest 
growths over these tracts, and the entire absence of even isolated 
ay tered savannas, as will be de- 
scribed thier ie Third, the south side of the island, outside 
