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THE AMERICAN NATURALIST [Vol. XLI 



and fourth, and is more conspicuous than that of the European 

 form from Sansan. In Moropus as in " Ancylotherium " this 

 large ungual has a comparatively limited dorsal flexure, as there 

 is a shoulder near the dorsal border of the distal trochlea of this 

 duplex bone and a corresponding buttress on the articulation of 

 the terminal phalanx; thus furnishing additional strength in the 

 use of this digit. 



Hind Limb.— The pelvis (No. 1706) of Moropus may be re- 

 garded as long and narrow. In comparing it with that of Perisso- 

 dactyla generally it is relatively longer in the region back of the 

 acetabulum, which feature is artiodactyl rather than perissodactyl. 

 Altogether, the pelvis of Moropus most nearly agrees with that of 

 Aceratherium tridactylum. As in the latter genus, the neck of the 

 ilium is long with a rapid expansion near the supra-iliac border, 

 but this border is less emarginated than in Aceratherium. In 

 Moropus the acetabulum is deep, and the pit for the round ligament 

 is of large size and is confined to the region back of the median 

 line. The obturator foramen is ovate in outline and of medium 

 large size. The pubic symphysis is quite strong anteriorly, but in 

 No. 1706, Carnegie Museum Cat. Vert., Foss., the ischium di- 

 verges outwardly more than is usual in other specimens.^ As 

 stated elsewhere, the femur has a strong third trochanter, which 

 is located above the middle of the shaft. The bone as a whole 

 resembles that of Titanotherium, but is relatively heavier and 

 shorter. The tibia is short and heavy; it is about four-fifths 

 the length of the femur. The articular facets for the femur are 

 divided by a prominent spine, the cnemial keel is heavy and extends 

 well down on the shaft, and the distal trochlea is characteristically 

 rhinocerotic. The fibula is complete, but its shaft is comparatively 

 delicate and has an even curvature from above downward so that 

 it lies close to the shaft of the tibia throughout; the distal end 

 extends below the external articular facet of the tibia and articu- 

 lates with the astragalus, but does not always touch the calcaneum.^ 



