EVOLUTION OF THE SKELETON OF EOCENE AND OLIGOCENE TITANOTHERES 



681 



Measurements of manus 



Millimeters 



Manus, lunar to D. Ill, phalanx 3 240 



Transverse, across carpals 150 



Scaphoid, breadth 65 



Scaphoid, height 45 



Lunar, breadth 50 



Lunar, height 40 



Trapezoid, breadth 40 



Trapezoid, height 29 



Magnum, breadth 48 



Magnum, height 31 



Unciform, breadth 77 



Unciform, height (maximum) 41 



Hind limb. — The total height of the hind limb from 

 the femur to the bottom of Mts III is estimated 



Lower Oligocene titanotheres of dolichopodal (rela- 

 tively narrow-footed) and swift-limbed type. 



Menodus heloceras? (Cope) 



The specific reference of the finely preserved pes of 

 Menodus in the American Museum (No. 1080) is 

 somewhat doubtful, but there can be no question 

 that it belongs to one of the small and primitive 

 species of that genus {M. heloceras or M. proutii). 



The family characters are well marked — namely, 

 (1) large fibulocalcaneal facet; (2) large tibio- 

 calcaneo-astragalar facet; (3) widely separated "sus- 



FiGURE 613. — Pes of Menodus trigonoceras, referred, and M. heloceras 



Ai, FroDt view of pes of M. trigonoceras (Am. Mus. 1079), with ectocuneiform and Mts IV restored. (This pes was 

 associated with the manus shown in fig. 614, A.) Aj, The same, phalanges of D. Ill, front view. B, Front 

 view of pes of M. heloceras (Am. Mus. 1080, reversed). One-fourth natural size. 



as 1,170 millimeters. The femur is short, length 

 560 millimeters, circumference of shaft 230. The 

 tibia also is very short (345 mm.). 



Measurements of the pes 



Millimeters 



Total length, os calcis to D. Ill, phalanx 3 320 



Width across astragalus and caleaneum 100 



Calcaneum, length 140 



Caleaneum, greatest breadth 93 



Astragalus, length (vertical) midline : 60 



Astragalus, breadth 82 



Cuboid, vertical height, midline 27 



Cuboid, breadth 60 



Navicular, vertical height 20 



Navicular, breadth 63 



Mts III, height 155 



tentacular, " " ectal, " and "inferior " astragalocalcaneal 

 facets; (4) displacement of Mts III against cuboid 

 and of Mts IV against ectocuneiform, displacements 

 that are very slight and that indicate the primitive 

 character of this pes. 



The generic characters of Menodus are equally well 

 marked — namely, (1) pes relatively long and narrow, 

 or elevated, in all its elements; (2) long axis of 

 tuber calcis extended obliquely anteroposteriorly, not 

 transversely as in Brontops, the tuber terminating in 

 a rounded suboval head; (3) sustentaculum of calca- 

 neum slender and downwardly directed; (4) cuboid 

 relatively narrow, vertically extended, with slight 

 lateral abutment against Mts III; (5) mesocuneiform 



