478 PATAGONIAN EXPEDITIONS I PALEONTOLOGY. 



This species is distinguished by its smaller size and more delicate pro- 

 portions. P A varies much in size, but has constantly a prominent ante- 

 rior pillar, which is set off by grooves on each side, and is better devel- 

 oped than in E. montana, or excavata ; the posterior process of m- is also 

 variable, but is constantly smaller than in E. montana and may be quite 

 rudimentary. P T is small, the anterior lobe smaller than the posterior 

 and grooved, though, as usual, this groove varies much in depth and dis- 

 tinctness. The skull is elongate and slender, notably lighter than that of 

 E. montana. 



Several limb bones were found in association with one of the skulls ; 

 they resemble those of E. excavata in form, but are somewhat lighter and 

 smaller; the only important difference is the greater reduction of the 

 fibula in E. fier/orata, the shaft being extremely slender. 



MEASUREMENTS. 



No. 15,010. No. 15,463. 



Upper dentition, length 035 



lf " pA-mi 0145 .0145 



Upper incisor, width 0025 .0023 



" " thickness 0033 .0033 



P-*., length (i. e., antero-posterior diameter) 003 .003 



" width (i. e., transverse diameter) 0035 .003 



Lower dentition, length 035 



" Pr- m * OI S 



Lower incisor, width 0023 .0023 



" " thickness 0025 .003 



P ? , length 003 .003 



" width of anterior prism 002 .002 



Skull, interorbital width 0165 



Rostrum, length 019 



" width at base oil 



" " " anterior end 009 



Palate, width at p*. 003 .003 



" " " m- 3 - 0075 .007 



Mandible, depth at pj 009 .008 



Scapula, antero-posterior diameter of glenoid cavity .007 



Femur, length from head .061 



" " " great trochanter .064 



" proximal width .015 



" distal width .012 



Tibia, estimated length .072 



" proximal width .on 



" " thickness . . .012 



