CO 
MEMOIRS OF THE CARNEGIE MUSEUM. 
75 59 73 67 50 
Vertical diameter of posterior face of centrum...................--...-- 70 48 65 55 40 
5 
Transverse diameter of anterior face of centrum................--.--..- 
Vertical (diameterofmeunallcanaly en meee nrc eee een eee ee 2: 22 22 22 20 
Transverse diameter of neuralicamalee sate ese el eeter: 23 22 Be 22 20 
Antero-posterior diameter of prezygapophysial surfaces................-. 39 22 at 27 20 
Vertical diameter of prezygapophysial surfaces..................-.-.--- 37 26 29 22 
Distance between prezygapophysial surfaces above................+---+ 46 47 me 44 25 
Antero-posterior diameter of postzygapophyses.................+--.0--. 37 24 be 30 21 
Perpendicular diameter of postzygapophyses..............-0-+0eeeeeee 30 23 ne 26 Pl 
Distance across postzygapophyses above............------++--++++ ees 50 40 es 44 35 
Mransverseldiameter ofpediceleey sane ine | eee eee 16 13 19 16 11 
Antero-posterion diameter olspedice eames nae nen eee eer 60 39 52 51 35 
Height of spine from neural canal to extremity.................+.--00-- 168 120 Spe = LANs) 
Antero-posterior diameter of spine above neural canal................... 68 52 ae 50 40 
Antero-posterior diameter of spine at top..............2+-0e--ee eee eee 62 50 is 50 se 
Height of metapophysis above prezygapophysial surface................. 20 15 af 20 10 
Height of end of metapophysis above transverse process...........-..--- 60 52 a 50 42 
Antero-posterior diameter of metayophysis below....................... 45 35 bes 42 29 
Antero-posterior diameter of metapophysis at end...............--.0--- 28 17 i 21 22 
Distanceracrossiendsiotametapophysesee see eeee see oEee eee 120 83 ry. 95 78 
The Third Lumbar Vertebra. 
Four examples of the third lumbar vertebra have been made the subjects of 
careful study and measurement. The largest of these is No. 1604, representing 
M. elatus, and belongs to the mounted specimen (see Fig. 68). It has sustained 
some injuries on the upper anterior edge of the dorsal spine, and at the ends of the 
metapophyses and transverse processes, but in no case are these so extensive as to 
make accurate measurements in most dimensions impossible. The specimen is 
practically perfect. No. 17038C is likewise an excellent specimen, belonging to 
M. petersoni, which has only required some minor repairs on the left postzyga- 
pophysis and at the ends of the transverse processes, which were a little broken 
(see Fig. 69). No. 1708 is the centrum of a specimen of M. elatus hardly inferior 
in size to No. 1604. It preserves the neural arch, both pedicels, and the left 
postzygapophysis; all the other superior processes have been lost, or badly broken. 
No. 1713 is a specimen of the third lumbar of a large but immature individual of 
M. elatus. 'The vertebra is perfect except for the loss of the end of the left trans- 
verse process, and the epiphyses of the centrum. 
The third lumbar in M. elatus is characterized by having the anterior edge of 
the dorsal spine above well produced forward; in M. petersoni the edges of the 
extremity of the spine are produced antero-posteriorly both before and behind. 
The spine is longer than in the second lumbar, The prezygapophysial surfaces 
