HOLLAND AND PETERSON: OSTHOLOGY OF THE CHALICOTHEROIDEA. ont 
1713 is that of a large, but immature, individual of M. elatus, which is practically 
perfect, except for the loss of the anterior and posterior epiphyses of the centrum. 
Specimen No. 1731 is the centrum of a comparatively small individual probably 
belonging to M. petersoni. All of the superior structures have been lost and only 
the bases of the transverse processes remain adherent. 
The fourth lumbar vertebra is characterized by having the anterior articu- 
lating face of the centrum subtriangular while the posterior face is vertically com- 
pressed, tending to become oval in outline, thus marking the beginning of the 
accommodation of the form of the centra of the lumbars for adjustment to the 
centra of the sacral series. The spine is greatly thickened and widened antero- 
posteriorly at its extremity and is slightly longer than that of the third lumbar, 
thus marking the highest point of the slight curve described by the extremities of 
the lumbars. The spine inclines very slightly backward. The prezygapophysial 
surfaces occupy nearly three-fourths of the anterior margin of the inner surface 
of the metapophyses. 
MEASUREMENTS OF FourTH LUMBAR VERTEBRA.” 
1708, 1703C, 1713, 1731, 
mm. mm. mm. mm. 
Greatest height from base of centrum to top of spine......................205. 263 198 230 
Greatest transverse diameter measured across transverse processes.............-. 230 171 182 
Greatest antero-posterior diameter measured from front of prezygapophyses to 
back-oleposizyeapopliyses aac. mms eters asp hve eke i os ae 128 99 105 a 
Heng chvoticentcumyalongsioor of meunalicanalsa-5 4.9.5 46924 oe dae 70 64 63 65 
enathrofcentrummalongameronsunacen ri iste esa eerste: 62 54 52 55 
Werticaltdiameter ofanterior taceok centrum. +.--.62+- 5.22.6 as secu. e 66 50 55 45 
Transverse diameter of anterior face of centrum.......................+..005- 77 65 72 64 
Vertical diameter of posterior face of centrum..................+...++-.-..00- 60 50 63 50 
Transverse diameter of posterior face of centrum...................2.0.000-5. 93 72 Uy 74 
Wernticaladiametermonneuralicanales mir er riiancs ists ae nly.ig ernie enn a 25 25 25 
transverse diameverorneuralicamalerscs ose hee ole ssd es selec cece ne: 25 30 25 
Antero-posterior diameter of prezygapophysial surfaces........................ 85 25 32 
Vertical diameter of prezygapophysial surfaces.................-.00eseeeeeeee 43 27 32 
Distance between prezygapophysial surfaces above.................000 0000 eee 50 40 43 
Antero-posterior diameter of postzygapophyses....................000eeeceeee 38 25 32 
Werticalediameterotipostaycapophysessans ac ye ot a ee 82 20 27 
Distance across postzygapophyses above....................-.---0eee eee ee 50 37 43 Be 
sbranserserdlame ters Oispedicelmra my atte Fl eicans Sey ice as) ici e me hoe ees ok 19 15 15 16 
PATIL ELOSDOSLCH OFd land CLETIOMmp CCC ler mm A tatyis eat ss easy yee tan 56 44 49 47 
Height of spine from neural canal to extremity.....................00...000-- 181 140 150 
Antero-posterior diameter of spine above neural canal......................... 68 50 56 
Antero-posterior diameter of spine at top..................0 0.00 cece eee ee 67 45 59 
48 Numbers in italics denote approximate measurements, the specimens being restored or broken. 
