HOLLAND AND PETERSON: OSTEOLOGY OF THE CHALICOTHEROIDEA. 309 
occupy fully two-thirds of the vertical height of the inner side of the metapophysis 
above the neural canal. The upper end of the metapophysis (mammillary process) 
lianas 5 
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Fic. 68. Third lumbar of M. ela- Fic. 69. Third lumbar vertebra of M. petersoni (No. 1703C). 
tus (No. 1604). xX. x4. 
is directed backward. The centrum in cross-section at the middle is subtriangular. 
In other respects this member of the lumbar series resembles the two vertebrz 
preceding it. 
MEASUREMENTS OF THIRD LUMBAR VERTEBRA.” 
1604, 1703C, 1708, 1713, 
mm. mm. mm. mm. 
Greatest height from base of centrum to top of spine...................+++-05- 260 197 oo Lae 
Greatest transverse diameter measured across transverse processes.............. 216 168 so | IGE 
Greatest antero-posterior diameter measured from front of prezygapophyses to 
backtolsposuzyecapop ly Sesrman seni Nae har.) Slaten Snes eMeec ata one 135 97 .. 104 
Mengthrorcentrumyalonestioor on neurallcanal 40. 4-.-+2...-. 266 soeesse esse. e 68 60 69 67 
Weng hvotecentrumyaloneunterornsurmacen nue nese oc ceeeice aoe 52 48 54 46 
Vertical diameter of anterior face of centrum...................0.... cece eee 77 52 75 61 
Transverse diameter of anterior face of centrum......................0--000-. 85 60 78 72 
Vertical diameter of posterior face of centrum......................0 ee eee eee 75 50 70 58 
Transverse diameter of posterior face of centrum......................--.05-- 93 67 85 85 
VWerticaliciameterommeuralicanale parc: trusses ee ec 5. Ses oo ates 24 24 25 25 
dransyerseqdiamererolmneuralucamalmenwrs sr ea: Manes. in. sate cack wean a: 24 25 a7 25 
Antero-posterior diameter of prezygapophysial surfaces........................ 46 27 ae 30 
Vertical diameter of prezygapophysial surfaces......................-.00000- 40 ih 35 
# Figures in italics are approximate measurements. 
