NO. 2127. 



OSTEOLOGY OF TEE8CEL08AURU8—GILM0RE. 



593 



Fig. 2.— Cervical vertebra of The- 

 scelosaurus neglectus gilmope. 

 Pakatype. No. 7758, U.S.N. M. J 

 NAT. SIZE. Ventral view. o. zyg., 

 Anterior zygapophyses ; d, dia- 

 POPHYSIS; p, parapophysis. 



In figure 1 is shown one of the cervicals from the posterior half of 

 the neck, which has a rather slender diapophysial process which ex- 

 tends outward, backward, and slightly downward. The anterior 

 zygapophyses have exceedingly broad 

 articular surfaces placed wide apart. 



While nothing is known as to the pre- 

 cise number of vertebrae m the neck, 

 there appears no good reason to expect 

 a greater number than in HypsilopJiodon 

 or CamiJtosaurus, the latter having been 

 definitely determined as having 9, which 

 agrees with Huxley's ^ determination of 

 the cervicals in Hypsilophodon, whereas 

 Hulke ^ shows in his restoration only 8. 

 Marsh ^ in his restoration of Hypsilopho- 

 don has certainly erred m increasing the number to 11. See plate 82. 

 The measurements of the centrum shown in figures 1 and 2 are: 

 Greatest length, 40 mm.; greatest width, anterior end, 41 mm.; 

 greatest height, anterior end, 27 mm.; greatest 

 width, posterior end, 33 mm. 



Dorsal vertebrae. — The dorsal centra are slightly 

 biconcave. In passing from the front toward the 

 sacrum the centra gradually increase in length 

 and in transverse diameter, reaching their maxi- 

 mum development in the last dorsal. 



The flattened ventral surfaces of the cervicals 

 change to a narrow rounded surface in the an- 

 terior dorsals, becoming progressively more and 

 more broadly rounded as they approach the sac- 

 rum. For a short distance on either end of the 

 centra, when viewed laterally, the surface is 

 longitudinally corrugated, being especially pro- 

 nounced on the ventral areas. The pinched-in 

 depression of the cervicals changes in the dor- 

 sals, so that posterior to the mid-thoracic region 

 the sides of the centra are approximately flat 

 in the vertical direction. AU are concave, how- 

 ever, longitudinally. All of the presacrals show 

 stout transverse processes. In the anterior dorsal 

 region these are relatively long (see fig. 3) with 

 a capitular facet on the side of the arch. Pro- 

 ceeding posteriorly the transverse processes become shorter and the 

 position of the facet changes from the side of the arch to the front 



> Quart. Journ. Geol. Soc. London, vol. 26, 1870, p. 3, pi. 1. 

 » Philos. Trans. Roy. Soc. London, 1882, pp. 1035-1062, pi. 82. 

 5 Dinosaurs of North America, 1896, pi. 84. 



81022°— Proc.N.M.Tol.49— 15 38 



Fig. 3.— Futeenth pre- 

 sacral vertebra, 

 probably the 2d dor- 

 sal of Thescelosaurus 



NEGLECTUS GiLMORE. 



Type. No. 7757, U.S.N.M. 

 § NAT. SIZE. Lateral 



VIEW. d, DIAPOPHYSIS- 



p, parapophysis; «, spin- 

 ous process; ««,neuro- 



CENTRAL suture; 2, AN- 

 TERIOR ZYG apophysis; 

 z', posterior zygapoph- 



YSIS. 



