310 MEMOIRS OF THE CARNEGIE MUSEUM. 
Distance between prezygapophysial surfaces above..................--+.--.-- 50 46 Ee 42 
Antero-posterior diameter of postzygapophyses......................-+++s02-: 34 25 30 28 
Vertical’ diameterjof postzycapophyseses 4 anes tee eee ee er 31 21 34 30 
Distance across) postzygapophyses|abovesns=. een eee ene 42 40 56 48 
Transverse diameter ofipedicel’.5: 5 eee ee ee eee 15) 14 16 15 
Antero-postenior diameter or pedicel ames eis eta eee nee eee 55 44 50 52 
Height of spine from neural canal to extremity.........2.......-.+.:..5) see: 172 =136 sea, lob 
Antero-posterior diameter of spine above neural canal................--....++- 67 53 Be 59 
Antero-postenior diameter-ot spinejat copa. eae eee Seen eee ene eee 64 50 fs 55 
Height of metapophysis above prezygapophysial faces.....................005 15 13 why 14 
Height of metapophysis above transverse procesS.................0e0eeeeeeee 65 51 oe 65 
Antero-posterior diameter of metapophysis below...................+-+-++000- 42 34 38 36 
Antero-posterior diameter of metapophysis at end....................e+0e000- 25 22 se 22 
Distance across/endsjof metapophyseshenss 5 ee seen ane eee eee 114 77 so LOW) 
The Fourth Lumbar Vertebra. 
Four specimens representing the fourth lumbar vertebra have been made 
the subject of study. The fourth lumbar of the mounted specimen was missing. 
The centrum of specimen No. 1708, an individual of very nearly the same size as 
specimen No. 1604, was therefore selected as the basis for the restoration. It 
retains in addition to the centrum the bases of the transverse processes, the 
origins of the metapophyses, and the greater part of the neural arch. With the 
other excellently preserved specimens before him Mr. Peterson was able readily 
to effect a restoration which fulfills all requirements. Specimen No. 1703C repre- 
senting M. petersoni is practically perfect, except that it has lost the extremity of 
the right postzygapophysis which has been restored (see Fig. 70). Specimen No. 
Tic. 70. Fourth lumbar vertebra of I. petersoni (No. 1703C). 3. 
