THE >r\MMALlA OF TIIK UINTA FOIJMATIOX. 



539 



metapodials and peculiar carpal displacement, a foot type adapted to animals of heavy 

 bulk, really present a striking analogy to the Proboscidia and an intermingling of 

 primitive with acquired characters. 



rhrmirodiis 



JIaslcflon 



Den c/ro/tymx 



Dl.vr.. ft. — The (lisplacoracnt of the bones of the manus in the Ungulata, I. Phenacoiui firimtctu*, from oritcinal 

 in the Cope rolleclion. Coryphodon hamatus, after Marsh. Dendrohyrai arboreus, from original in the Prinrcton col- 

 lection, .ffaerauc/ienia pnliichonica, ader GcrvMs. Mastodon Americanus from originalia Princeton collection. The 

 oblique arrows indicate the direction of displacement. 



3. Pkobosctdia. 



"Weithofcr* has recently directed attention to the unirpie depart iire from tlic 1a\- 

 eopod condition of the carpus in this oixlcr — the lunar s[)reading uj)un the trapc/.oid, 

 i. e., to the ental side, instead of upon the magnum. In M(txln(lon arvevnens/'s, Ele- 

 phcis meridionalis and E. antiquum from one-fourth to one-liftli of tlie inferior face of 

 the lunar rests upon the trapezoid. We find the same condition in Mastodon Amen'canus. 



This author attributes this to the enlargement of the ulna and its extension upon 

 the lunar r.'*. the radial enlargement in all other ungulates. This displacement is 

 varial>le, since it actually recedes and sometimes disappears (<>]>. n'f.. p. "l") in I he 

 adult recent forms {E. Indims, E. Afrlcamis). Burmeister moreover has figiuedf 

 the carpus of a specimen of M. ILimhohllii, in which the lunar pj)rcads both upon 

 the trapezoid and magnum. Another primitive feature of the carpus is the recently 



• Einigc Btmcrkiinjren fiber den Cnr|)ii8 der Probosrjdicr. Morph. .Jahrb., 1888, p. liOr. 

 f Ann. del. Miis. Publ. d. Bucn. Ayrcs, Plate XIV, p. 287. 



