104 Annals of the Carnegie Museum. 



Princeton University. The result of my work convinced me (i)_that 

 there are two distinct lines of tapir-like animals, or pseudotapirs, in 

 the Eocene of North America, which hold a position parallel to the 

 Lopliiodontidce of the European Tertiary; (2) that the decision reached 

 by Scott, Osborn, Wortman and Earl that the Helaletids are not true 

 ancestors of Tapirus is confirmed; (3) that the view that Isectolophus 

 may be regarded as in the ancestral line of the recent tapirs is not 

 substantiated, but that this Uinta genus represents a distinct side- 

 or secondary line of pseudo-tapirs in the American Eocene; and (4), 

 that, with the possible exception of Dilophodon minusculus, we have 

 not yet discovered in the American Eocene the true ancestor of the 

 Oligocene and recent tapirs. 



Subfamily TAPIROIDEA Gill. 



Family HELALETID.E Osborn and Wortman. ^^ 



This family includes Heptodon of the Wasatch and Wind River 

 Eocene; Helaletes boops, H. nanus, Dilophodon minusculus of the 

 Bridger Eocene, and probably Colodon of the Oligocene. Dcsmato- 

 thcrium of the Bridger Eocene should be excluded and placed in the 

 line of the Rhinoceroses, vide p. 127, or more correctly in the family 

 Hyracodontida. 



Subfamily HELALETIN.E. Wortman and Earl.'i 



Small perissodactyls with large anterior nares and air-sinuses analogous 

 to those in the recent tapir; cross-crests of loiver molars perfectly developed; 

 no connecting crests betiveen proto-, and hypoconids; hypoconulid small or 

 absent; incisors subeqiial in size; limbs long and slender and of more 

 nearly equine than tapiroid structure; astragalar trochlea very oblique. 



Genus Helaletes Marsh. 

 32. Helaletes boops Marsh. (Plate XLII, Figs. 1-9; Plate XLIII, 



Figs. 1-3). 

 Amer. Jour. Sci., Vol. IV, 1872, p. 218. 



Type: Considerable portion of the skull, lower jaws and other frag- 

 ments of the skeleton. No. 11807, Peabody Museum Catalogue. 



Horizon: Bridger Eocene. 



Locality: Grizzly Butte, Wyoming. Yale Expedition of 1S71. 



^^ Bull. Amer. Mus. Nat. HisL, Vol. IV, 1892, p. 127. 



"' L.c, Vol. V, 1893, P- 173- 



