52 



centrum is constricted at mid-length so as to have concave sides and lower surface, there 

 being at either end of the latter a broad median groove. The neural arch does not reach 

 far below the top of the centrum. The diapophyses (imperfect in the specimen) 

 have stout bases, relatively broad in their antero-posterior diameters. The faces of the 

 prezygapophyses are directed obliquely inward. The neural spine is well developed, 

 short, deep from back to front, shallowly concave on its sides, with rugose, slightly 

 excavated, anterior and posterior surfaces. The centrum is hollow, its walls dense and 

 about 25 mm. thick at mid-length, the inner space extending to within about 6 mm. of 

 either end. 



The caudal vertebra3, plate XIV., figs. 2—5, and plate XV., figs. 1 — 5, supposed to 

 belong to this species, are remarkable for the suppression of the neural spine and the for- 

 ward horizontal extension of the prezygapophyses to a distance in advance of the anterior 

 end of the centrum nearly equal to the length of the centrum itself. The postzygapophyses 

 are represented by a backwardly directed, laterally compressed, nearly horizontal process 

 that fitted between the prolonged prezygapophysial processes of the succeeding vertebra. 

 The centrum is long compared with its height, slightly concave on its sides and lower 

 surface, with a strong median groove below. In different specimens its interior may be 

 moderately hollow or instead a number of vacuities of variable size may be present. 

 Small facets, for the attachment of the chevron bones, are present at the lower, posterior 

 ends of the centra ; these are not recognized at the anterior ends. The neural spine is 

 sometimes represented by a narrow, rounded ridge (shown at " w " in the specimen 

 figured on plate XV., fig. 2). The prezygapophysial processes are broadly expanded later- 

 ally, contracting and thinning gradually anteriorly, their outer edges overhanging the 

 sides of the anterior end of the centrum and extending lower than the median upper 

 surface of the same ; their lower surfaces are slightly striated longitudinally. The 

 neural canal is small, its outlet, anteriorly, is wider than high and is roofed over to a 

 point above the anterior end of the centrum. These caudal A^ertebrte indicate a tail of 

 considerable length but their manner of articulation would scarcely admit of much 

 lateral motion. 



A nvxmber of phalanges of the supposed manus of this species are also hollow but 

 present a difference in the shape of the terminal phalanges which are curved and 

 laterally compressed with a groove on each side extending from the apex backward and 

 dividing into two branches toward the proximal end. Judging from the size of these 

 phalanges the manus was smaller than the pes, and their shape suggests a grasping 

 capacity ; the terminal phalanges were probably encased in sharp, hooked claws giving 

 their possessor the power of tearing its prey. 



Two bones, probably the distal ends of the first metatarsal* and the first metacarpal, 

 were found with, the phalanges of the manus above referred to, phalanges of the pes, a 

 separate astragalus and a calcaneum. 



* "Fore and Hind Limbs of Carnivorous and Herbivorous Dinosaurs from tlie Jurassic of Wyoming," Bulletin Am. 

 Mus. Nat. Hist., vol. xii., 1899, by Henry Fairfield Osboin, figs. 3, i and 4a. 



