NO. lOtiti. OlSTEULiXiy OF CAUFTOlS.iURLlS—GlLMORE. 229 



There is a well-developed capitular process on the side of the 

 centrum near the anterior end just below the neuro-central suture, 

 and a weak tubercular process near the middle lateral surface of the 

 neural process, posterior and below the level of the prezygapophyses. 

 As in the axis the neural canal is largo, being higher than wide, with 

 thin walls. 



The postzygapophyses are a pair of slender, divergent processes 

 which extend upward, backward, and outward, their articular faces 

 looking downward and outward. A low, median crest of bone rises 

 posterior to the bases of the prezygapophyses and extends posteriorly 

 to the dividing point of the branches of the zj^gapophyses. 



Ce?'vicals posterior to the third. — Marsh has observed:" "The cer- 

 vical vertebrae are all opisthoccelous." In this he was evidently mis- 

 taken, as is clearly shown by a study of several individuals which 

 have the complete cervical region preserved. The axis and third 

 cervical are always- j)latycoelian. In most individuals, however, the 

 remaining cervical centra are opisthocoelian, though more strongly so 

 in the posterior than in the anterior cervicals. In Cat. No 54T4, 

 U.S.X.M., the cervical centra, comparatively speaking, remain quite 

 plane throughout the series. 



VicAved from the anterior end, the centra are shield-shaped (see 2, 

 fig. 14). Below the neuro-central suture the sides are deeply pinched 

 in, forming lateral depressions which are deeper toward the front, 

 and concave in the longitudinal direction, the articular ends being 

 exjDanded. Ventrally there is a strong angular keel which widens 

 at either end, more especially the posterior. The ventral surfaces of 

 the ends are roughened by coarse, irregular, longitudinal striae. All 

 of the cervicals have capitular facets on the sides near the anterior 

 end (see p, fig. 14). In the anterior region the facets are just below 

 the neuro-central sutures, but in the posterior cervicals, beginning on 

 the fifth in Cat. No. 5473, U.S.N.M., the suture bisects the facets, 

 and thus both the centrum and the neural arch contribute to their 

 formation. 



The neurapophyses in all of the cervicals have an extensive attach- 

 ment to the centrum, spreading out conspicuously at the ends, more 

 especially the anterior, as shown in fig. 14. 



Well-developed diapophyses extend outward from the sides of the 

 neura- and prez3'gapophyses, shown at d, fig. 14. These gradually in- 

 crease in length from the third to the ninth. The tubercular facets 

 on their outer extremities look downward and outw^arcl. The neural 

 canal remains large throughout the neck, becoming nearlj'^ circular in 

 the posterior members. The prezygapophyses are wide apart, their 

 articular faces looking inward and upward. Neural spines are not 



»Amer. Journ. Sci.. XVIII, Dec, 1879, p. 501. 



