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Each haemapophysis is a long slender conical bone, with an articular surface at each 

 angle of the base, hy 1 , hi/', and an obtuse slightly inflected apex : the inner side of 

 the bone is slightly concave, the outer one convex transversely : a rough tuberosity 

 dividing it from the inflected apex. The essential differences between the first caudal 

 segment and the dorsal one delineated on the same Plate are, that the pleurapophy- 

 sis, pi, is short and anchylosed to the diapophysis, the haemopophyses, h, articulate 

 with the centrum, and the haemal spine is absent, in fig. 2. 



The second caudal vertebra (Plate VIII. figs. 1 and 2) differs from the first in 

 having an anterior, fig. 2, hy, as well as a posterior, ib. hy', pair of hypapophyses ; 

 and in the confluence of the haemapophyses, fig. 1 , h, at their apices forming the so-called 

 ' chevron bone' (os en chevron, Cuvier). This vertebra is smaller than the first caudal 

 in all its parts except the haemapophyses, and in all its dimensions except the vertical 

 diameter, which is due to the development of the coalesced parts of those elements 

 into a long and strong haemal spine, hs. The anterior hypapophyses, fig. 2, hy, which 

 are the smallest, articulate with the surface on the back part of the base of the haem- 

 apophyses of the first caudal vertebra : the posterior hypapophyses, hy', which are 

 more oblong and closer together, articulate with the anterior and larger pair of sur- 

 faces, hy', of their own haemapophyses, fig. 1, h. There is a strong rough tuberosity 

 projecting backwards external to each of the anterior hypapophyses. The posterior 

 articular surface is, in the present instance, developed only on the right haemapo- 

 physis, fig. 1, hy"; on the left it is represented by a rough tubercle. 



From the third to the fifth caudal vertebrae inclusive, the proximal end of each 

 haemapophysis has both the large anterior transversely oblong surface for its own 

 centrum, and the smaller subcircular posterior surface for the next centrum : the 

 spine, or coalesced portions, of the third pair is the longest in the caudal series ; be- 

 yond this it progressively diminishes. In the sixth caudal vertebra the haemapo- 

 physes have a rough protuberance instead of the posterior articular surface. After 

 the eighth the protuberance subsides to a rough ridge. In the eleventh caudal 

 (Plate VIII. figs. 3-6) the distal end of the coalesced and shortened haemapophyses, 

 hy, is truncate, and as broad as the divided bases. The under surface of the corre- 

 sponding centrums of the sixth to the eleventh caudal offers the articular surface on 

 the anterior pair of hypapophyses, fig. 6, hy' ; the posterior pair, ib. hy, are rough 

 tuberosities. The posterior zygapophyses (figs. 3, 4, 5, z' z') retain their articular 

 surfaces to the tenth caudal: in the eleventh they are mere angular projections. The 

 metapophyses, mm, are continued to the fourteenth caudal. The neural spine is 

 reduced to a low tuberosity on the thirteenth caudal (fig. 7, ns): the neural arch con- 

 tinues complete to the sixteenth, fig. 8, n: in the seventeenth, fig. 10, the neurapophyses, 

 ii, are mere exogenous ridges, bounding the sides of an open neural groove. The 

 haemapophyses are continued to the fourteenth vertebra: two pair of rough low 

 hypapophysial tubercles, hy, hy, fig. 9, continue to be developed to the sixteenth : 

 they subside on the penultimate caudal, fig. 11, in which the diapophyses are repre- 



