304. MEMOIRS OF THE CARNEGIE MUSEUM. 
neural arch and a considerable portion of the spine, were utilized in restoring the 
last three vertebree of the series. ‘The lumbar series in the mounted specimen 
consists therefore of the three anterior lumbars belonging to No. 1604 and the last 
three centra of No. 1708. No. 1703C is a series of six lumbar vertebree which were 
found in the same locality and which are discovered to exactly fit each other, so as 
to leave hardly any room whatever for doubt that they belonged to the same indi- 
vidual. Specimen No. 1713 also supplied a series of six lumbar vertebrae very 
well preserved in all respects, except that they have all lost the anterior and pos- 
terior epiphyses of the centra. 
In addition to the four series above mentioned a number of other lumbar 
vertebre not forming a series were discovered. Their dimensions will be given. 
The spines of the lumbar vertebree when they are arranged in regular serial 
order in all cases describe a gentle curve rising from the first to the fifth vertebra 
and then declining so as to coincide approximately in height with the extremities 
of the sacral vertebree. The spines, viewed laterally, are greatly flattened in an 
antero-posterior direction, strongly rugose at their upper extremities, and vertical 
in position. The metapophyses are broad, projecting upward and forward. The 
transverse processes are broad, flattened, projecting horizontally outward, except 
in the ease of the last lumbar, which is considerably thickened and projects some- 
what forward, to conform with the anterior margin of the ilium. The centra of 
the first four lumbars in vertical section are more or less subtriangular, the last 
two are greatly flattened and compressed vertically and more or less oval in cross- 
section, thus approximating in outline the form of the centra in the sacral vertebre, 
which are likewise greatly compressed vertically. The prezygapophyses are 
formed on the anterior face of the upturned margin of the laminze below the point 
where the metapophyses have their origin, are concave, and look upward, inward, 
and forward. The postzygapophyses are laterally convex, look downward, out- 
ward, and backward and greatly overhang the posterior face of the centrum. 
First Lumbar Vertebra. 
Seven specimens of the first lumbar were found. Of these No. 17038C is re- 
ferred to M. petersoni, the others to M. elatus. No. 1604 belongs to the mounted 
specimen and is in an excellent state of preservation (see Fig. 64). No. 1708 is a 
centrum preserving with it portions of the neural arch and the right metapophysis 
and transverse process. Specimens No. 1604 and No. 1708 pertain to old and 
fully adult specimens of M. elatus. No. 1713 is the first lumbar of a large but not 
fully matured specimen, the epiphyses of the centrum having been lost. Nos. 
