502 HARRY GOVIER SEELEY ON THE 



ward ; it is imperfectly preserYed. Small zygapophysial facets (fig. 8g) 

 are preserved or indicated both in front and behind. The neural 

 spine (fig. 8 e), as preserYed, is thicker posteriorly than in front, 

 does not extend quite to the anterior border of the neural canal, 

 and posteriorly is cleft vertically. Specimens of Enaliornis SedgwicJci 

 (fig. 13) show the centrum to be considerably impressed laterally 

 below the transverse process * 3 and that the neural canal is much 

 wider than high ; the neural spine is directed somewhat backward. 

 The shortest centrum is more than | inch long. The amount of the 

 concavity of the centrum varies. 



Hie Sacrum. (PI. XXYI. figs. 14-19.) 



There are three fragments of the sacrum in the Woodwardian 

 Museum, and a fourth (from the posterior part of the sacrum) in the 

 collection of James Carter, Esq., M.R.C.S. The Woodwardian spe- 

 cimens appear all to belong to the same genus, are in sequence to 

 each other, and show the sacrum to have been constructed exactly 

 after the water-bird pattern. The vertebrae, however, are more 

 elongated, so that the sacrum is much longer in its several regions 

 than are the corresponding parts of the sacrum of the Diver. The 

 first fragment (fig. 14) comprises the first, second, and part of the third 

 sacral vertebrae anchyloscd, with the elevated margins of the con- 

 fluent centrums unusually well marked on the basal border. The 

 first centrum is depressed, with the articular surface flattened in 

 front, as in the Gulls and the Gannet, and somewhat concave cen- 

 trally. The anterior articulation is nearly -| inch broad. The 

 centrums increase a little in length from before backwards ; the 

 first is about T % inch long, with a depressed form of centrum, broad 

 and convex from side to side, and slightly concave from back to 

 front. I am unable to detect any indication of the diapophysial 

 articulation on the anterior border of this centrum usually to be 

 seen in existing birds. A narrow transverse process, J inch wide, is 

 given off from the anterior part of the side of the centrum and 

 directed outward and somewhat upward ; its outline is emarginate 

 both anteriorly and posteriorly. In the succeeding vertebrae the 

 centrums become a little deeper, and rapidly more compressed from 

 side to side, the third having the sides flattened, and base forming a 

 narrow rounded ridge. The third vertebra shows the transverse 

 processes, which, thick and strong, appear to have formed horizontal 

 neural tables, the bases of which, as preserved, have a transverse 

 measurement of | inch. From the neural platform to the base 

 of the centrum is more than -| inch. No indication of the neural 

 spine is preserved. 



The second specimen (figs. 15, 16), from the middle of the sacrum, 

 is in a pale state of mineralization, andjmore free from matrix. It 

 was collected by M. E. Pryor, Esq., late Eellow of Trinity College. It 



* The impression is never as deep as in Gulls, or even as in the Wealden 

 fossil Ornithopsis, a genus so named from the resemblance of its centrum to 

 that of certain Grulls. 



