1881. ] on the Feet of Mammalia. 547 
flexure of the joint. (2) They fit entering grooves of the proxi- 
mal ends of corresponding bones. These will be the result of the 
same application of force and displacement, as the protrusion of 
the oe commencing with a concavity (Elephas); becoming 
Fic. -9. Fic. 10. Fic It, 
'_ Fic. 9.—Part of args foot of Procamelus identalis from, New Mexico. From 
Report of Capt. G. M. Wheeler, Vol. Iv, “i i. 
FiG, 16 — Mat als of Cosoryx far espe from abosstirsrt two thirds natural size; 
a, ce face; 2, Sosterior ; ¢, prox end ; d, distal end. 
pie eft forefoot with part 7 a of ResmneT vilsont Leidy, from 
. prado, ace: fifths natural size. From Hayden’s Report, Iv. 
More concave (Fig. 7), and becoming finally a groove. (3) When 
the dense edge of a bone, as in the case of the lateral walls of the 
“Astragalus, is presented upwards, a groove is produced in the 
