366 E. L. Troxell— Helaletes Redefined. 



rect reference it saves the species. Helaletes nanus 

 Leidy does not exist and it is doubtful whether he 

 intended to create a new species in his original descrip- 

 tion, for he mentioned Lophiodon nanus Marsh at that 

 time. 



Helaletes nanus (Marsh). 



(Fig. 1.) 



Holotype, Cat. No. 11080, Y. P. M. Eocene (Bridger), Grizzly Buttes, 

 near Fort Bridger, Wyoming. 



Lophiodon nanus was one of the first three lophiodonts 

 described by Marsh; it is based on the two weathered 

 maxillaries, the right one of which bears all the cheek 

 teeth except P 1 , whose root only remains (see Fig. 1). 

 Following is the original description in part : 2 



"The molars differ especially from those of the two preceding 

 species [Hyrachyas bairdianus, H. affinis] , in having a much 

 shallower valley between the two transverse ridges, and in hav- 

 ing a strong basal ridge, or shelf, at the external posterior cor- 

 ner of the crown. The enamel of the whole series is very 

 smooth. The species was probably about two-thirds the size of 

 L. modestus. 



Fig. 1. 



Fig. 1. — Helaletes nanus (Marsh). Holotype. First described by Pro- 

 fessor Marsh over fifty years ago. Note the double internal cusp of the 

 premolars. Nat. size. 



Measurements. 



Length of upper jaw, containing seven pos- 

 terior teeth 26.0 lines [55.0 mm.] 



Length of same, with three last molars. . . . 13.7 lines [29.1 mm.] 



Antero-posterior diameter of last upper 



molar 5.0 lines [10.6 mm.] 



Transverse diameter of same 5.25 lines [11.1 mm.] 



"The remains now known to represent this species were dis- 

 covered by C. W. Betts, H. B. Sargent, and the writer, in the Ter- 

 tiary strata at Grizzly Buttes, near Fort Bridger. ' ' 



2 Marsh, O. C, This Journal (3), 2, 37, 1871. 



