NO. 7 EARLY CENOZOIC VERTEBRATES FRIES ET AL. 21 



cusps. The anterior cingulum of Mi is better developed than that of 

 Mo. The size and shape of the teeth and their cusp development are 

 like those of the holotype. 



MEASUREMENTS OF HOLOTYPE (l.G.M. NO. 52-I37) OF FLORESOMYS 

 GUANAJUATOENSIS, NEW GENUS AND SPECIES 



Mm. 



P'-M^ anteroposterior length 5.3 



P*-M^ anteroposterior length 5.1 



M'-M^ anteroposterior length 4.3 



P*, greatest anteroposterior length i.o 



P*, greatest tranverse width i.o 



M\ greatest anteroposterior length 1.5 



M\ greatest tranverse width 1.5 



M^, greatest anteroposterior length i.S 



M'', greatest transverse width i .6 



M', greatest anteroposterior length 1.5 



M"', greatest transverse width 1.4 



Depth of ramus at Mi 4.3 



Depth of ramus at M3 4.1 



Distance from incisor alveolus to tip of condyle 7.5 



Length of diastema, between incisor and P4 2.6 



Fi-Ms, anteroposterior length 5.33 



M1-M3, anteroposterior length 4.3 



P4, greatest anteroposterior length i.i 



P4, greatest transverse width 0.8 



Mi, greatest anteroposterior length 1.4 



Ml, greatest transverse width 1.2 



M2, greatest anteroposterior length i.S 



M2, greatest transverse width i.S 



M3, greatest anteroposterior length 1.4 



Ms, greatest transverse width 1.3 



The cheek teeth of Floresomys appear to be higher crowned than 

 other specimens of sciuravines with which it was compared; this 

 may be due to the small size of F. guanajnatoensis and the age of the 

 specim.ens. The genus is named in honor of Ing. Teodoro Flores, 

 director of the Institute of Geology of the National University of 

 Mexico. 



OtJier specimens. — In August 1950, Fries recovered parts of two 

 fragmentary rami and the anterior part of a skull, Instituto de 

 Geologia of Mexico No. 52-136, at the same locality where the 

 holotype was subsequently found. The two fragmentary rami are 

 parts of right lower jaws. The larger consists of the diastemal region, 

 part of the incisor and the alveoli, and roots of P4. This fragment 

 compares closely in shape and size with the paratype. The incisor is 



