Peterson: Material Discovered in Uinta Basin. 121 



ditiou described and illustrated by Osborn {op. cit., p. 521); /". e., that 

 the second and third premolars have two roots and Py one root. 

 The root of the canine indicates that tooth to be relatively larij;er that 

 in the American Museum specimen, No. 1828. 



Parisectolophus nom. nov. 

 (Type Parisectolophus latidens (Scott & Osborn).) 

 37. Parisectolophus latidens (Scott & Osborn). 



Isectolophus latidens Osborn, "The Mammalia of the Uinta Formation," 



Trans. Amer. Phil. Soc, Vol. XVI, 1889, p. 513 el seq. 

 Helaletes lalidens Scott & Osborn, E. M. Museum Bull., Princeton Univ., 1878, 

 p. 54. No. 3- 



(Plate XLIV, Figs. 2-3). 



Type specimen: Upper and lower jaws, No. 10251, Natural Science 

 Museum, Princeton University. {Cf. Osborn, L.c, p. 518.) 



Horizon: Middle Eocene. 



Locality: Henry's Fork? Wyoming. 



Principal Characters: /-j, C-y, P-f, ikff, P-, with tivo internal tubercles; 

 P- -liith one internal tubercle; light cingula on anterior, posterior, and 

 external faces of premolars and molars. Mela- and paracones subcorneal; 

 paracone larger than metacone; parastyle large and luell-separated from 

 paracone; cross-crests of molars obtuse and valleys shalloiv; extremely 

 short diastema between Py and P-j. Inferior canines comparatively 

 robust. Hypoconidid of M-^ well-developed; connecting crests between 

 proto- and hypoconids of molars. Lower jaws quite thick and slightly 

 constricted back of canine and P 1. 



The most noteworthy differences between this genus and Helaletes, 

 as exhibited by the type specimen, are the following: in Parisectolophus, 

 the metacone is more subconical, the parastyle larger and more widely 

 separated, the cross-crests of the upper and lower molars more obtuse, 

 the hypoconulid of M^ longer, and the diastema between the incisors 

 and cheek-teeth absent (See PI. XLIV, Figs. 2-3). 



Parisectolophus latidens differs from Isectolophus in comparatively 

 few nevertheless well-marked and rather important characters, so 

 far as comparison can be made. First, the molars of Isectolophus are 

 considerably advanced, because of the greater posterior enlargement 

 of the ectoloph, making the para- and metacones equal in size; sec- 

 ondly the cross-crests of the molars are slightly higher and sharper; 

 the cingulum of the upper molars are much heavier. 



