18 



UNITED STATES NATIONAL MUSEUM BULLETIN 294 



(USNM 23794; pi. 9, fig. 5) has increased slightly. 

 The elongated nietapophyses, which rise 50 mm. above 

 the floor of the neural canal, project considerably be- 

 yond the level of the anterior face of the centrum. The 

 distal end of the left parapophysis (pi. 10, fig. 6) is 

 missing; the spatulate and dorsoventrally compressed 

 right {jarapophysis is complete, projecting outward 

 and downward from near the middle of tlie lateral sur- 

 face of the centrum. The backward slanting neural spine 

 (pi. 11, fig. 5) rises 200 mm. above the roof of the neural 

 canal and is bent leftward, deforming the neural canal. 

 The median longitudinal ridge is more strongly de- 

 veloped on the ventral surface of the centrum than on 

 the floor of the neural canal. No bony excrescences are 

 present. 



Sixth lumbar. — The extremity of the left para- 

 pophysis (pi. 10, fig. 7) is missing, but otherwise this 

 vertebra (USNM 23794) is complete. On this lumbar 

 the backward slanting neural spine (pi. 11, fig. 6) is 

 not only wider (minimum anteroposterior diameter, 

 78 mm.) than those on the preceding lumbars, but is 

 also longer, rising 208 mm. above the roof of the neural 

 canal. This neural spine (pi. 9, fig. 6) is less noticeably 

 bent leftward, although the neural canal is deformed 

 in that direction. Very little reduction in the length 

 of the dorsoventrally compressed subspatulate para- 

 pophysis or in the anteroposterior diameter of the thin 

 pedicle of the neural arch is discernible. The median 

 longitudinal ridge does not extend the length of the 

 ventral surface of the centrum ; no l)ony excrescences 

 are present. 



Sevknth lumbar. — A marked reduction in the size 

 and forward projection of the metapophy$es (pi. 11, fig. 

 7) and in the length (minimum anteroposterior diam- 

 eter, 65 mm.) of the thin pedicles of the neural arch, 

 as well as a .shortening of the parapophyses are the most 

 obvious distinguishing features of this lumbar (USNM 

 23694) . Most of the right parapophysis (pi. 10, fig. 8) as 

 well as the distal end of the neural spine are lost. The 

 transverse diameter (34 mm.) of the neural canal (pi. 9, 

 fig. 7) at the floor almost equals the vertical diameter 

 (35 mm.) anteriorly. The neural spine is essentially 

 vortical, not bent leftward as on preceding lumbars. A 

 medium longitudinal ridge is present on the ventral and 

 dorsal surfaces of the centrum. No bony excrescences 

 are present. 



Eighth lumbar.— The convex curvature of the 

 posterior edge of the thin outward and downward 

 projecting left parapophysis (pi. 10, fig. 9) accentuates 

 its slight forward direction, although its rounded ex- 

 tremity does not extend forward beyond the level of 

 the anterior face of the centrum (USNM 23794). The 



extremity of the right parapophysis is missing and both 

 metapophyses are incompete. The backward slanting 

 neural .spine (pi. 11, fig. 8) is vertical and rises 197 mm. 

 above the roof of the neural canal. The vertical diam- 

 eter (39nnn.) exceeds the transverse diameter (28 mm.) 

 of the neural canal (pi. 9, fig. 8). A median longitudinal 

 ridge is present on the ventral and dorsal surface of the 

 centrum. No bony excrescences are present. 



Ninth lumbar. — Measurements of the centrum 

 (USNM 23794) are not materially different from the 

 eighth lumbar. The neural canal of this lumbar (pi. 9, 

 fig. 9) has been reduced in width (24 mm.), the vertical 

 but backward slanting neural spine (pi. 11, fig. 9) , which 

 rises 187 mm. above the roof of the neural canal, has 

 been slightly shortened, and there is a slight increase in 

 the length (132 mm.) of the centrum. A sharp-edged 

 median longitudinal ridge is present on the ventral face 

 of the centrum; the corresponding ridge on the floor 

 of the neural canal is low. Both metapophyses are in- 

 complete and the extremity of the left parapophysis (pi. 

 10, fig. 10) is missing. The outward and downward 

 projecting parapophyses are inclined more strongly for- 

 ward than on the preceding lumbar ; these processes are 

 also slightly shorter and wider than those on the eighth 

 lumbar. No bony excrescences are present. 



Tenth lumbar.— This lumbar (USNM 23794; pi. 9, 

 fig. 10) lacks the roof of the neural arch, both meta- 

 pophyses and the neural spine. The dorsoventrally com- 

 pressed parapophyses (pi. 11, fig. 10) are approximately 

 as wide (75 mm.), but are slightly shorter than those of 

 the preceding lumbar and are deflected less obliquely 

 downward from horizontal. A portion of the extremity 

 of the left parapophysis (pi. 10, fig. 11) is missing; the 

 right process is complete. Decrease of the transverse 

 diameter (23 mm.) has been gradual. A sharp-edged 

 median longitudinal ridge is present on the ventral sur- 

 face of the centrum and a similar less elevated ridge 

 extends the length of the floor of the neural canal. 



Eleventh lumbar. — This lumbar was dislodged from 

 the vertebral cohnnn prior to the accumulation of the 

 protective overlying sediments and was not found asso- 

 ciated with the skeleton. 



Twelfth lumbar.— This lumbar (USNM 23794; pi. 

 9, fig. 11) lacks the roof of the neural arch, both 

 metapophyses, the neural spine, and all except the basal 

 portions of both the i)arapophyses. The length, width, 

 and height of this lumbar exceeds the corresponding 

 dimensions of all the preceding lumbars. Posteriorly 

 on the right side of the centrum (pi. 11, fig. 11) above 

 the parapophysis, a rather large, bony excrescence 

 projects backward about 30 mm. beyond the posterior 

 epiphysis. A sharp-edged median longitudinal ridge 



