BRITISH FOSSIL CRETACEOUS BIRDS. 501 



The lateral areas are concave ; the posterior articulation is slightly 

 concave in depth, and more convex in breadth : it is nearly square, 

 but broader above than below. The neurapophyses rise obliquely 

 from above the upper part of the centrum behind, widening supe- 

 riorly to above the neural canal in front. The depth in front of the 

 centrum and neural arch is more than -| inch. The upper surface 

 is obscured, and the neural spine is not preserved ; it does not rise 

 from quite the front of the arch, which is nearly horizontal above. 

 The facets for the zygapophyses look upward and inward. 



This specimen, in the collection of W. Reed, Esq., is not unlikely 

 to belong to Enaliomis Barretti. 



Dorsal Vertebrce. (PI. XXVI. figs. 7-13.) 



The four dorsal vertebrae in the "Woodwardian Museum, like all 

 the other specimens which have come under my notice, except Mr. 

 Reed's, agree in their characters, though they differ a little in size. 

 They are small in proportion to the size of the head, and show no 

 resemblance to any vertebra) of the Diver. Two of the centrums 

 of Enaliomis Sedgwicki (fig. 12a) display to some extent indications of 

 the peculiar Ichthyoid biconcave articular condition already referred 

 to ; but, as it is wanting from the largest specimen, it is possible 

 that the smaller specimens though adult are imperfectly ossified ; 

 many natatorial birds have the lower dorsal centrums nearly flat, . 

 while very young birds have a small central notochordal depression 

 on the articular face. The centrums are much less compressed from 

 side to side than is usual in the dorsal vertebra? of water-birds. 



The largest specimen, Enaliomis Barretti, has the centrum rather 

 more than J inch long, expanded at both articular ends, somewhat 

 flattened at the base and at the sides, which round into each other 

 (fig. 9), and are each concave from back to front. The anterior ar- 

 ticulation (fig. 11a) is -| inch broad and | inch deep. It is re- 

 markable for having the sides of the centrum prolonged forward for 

 a considerable distance, so that the surface is markedly concave from 

 side to side, while vertically the convexity, if it exists, is so slight 

 as to be scarcely detected. Posteriorly the articulation (fig. 10 b) is 

 necessarily narrower ; it is more than J inch wide and less than 

 ^ inch deep. It is convex from side to side, flat from above down- 

 ward, with a central concavity, is subquadrate, emarginate in the 

 upper part of the side, with a slight impression dividing the basal 

 margin. Laterally (fig. 7 c), at the side of the anterior border of 

 the neural arch is an oblique oval facet slightly elevated, J inch 

 long and concave, which has exactly the form and position of the 

 diapophysis in the vertebras of existing birds like the Gannet. The 

 whole centrum closely resembles that of the Solan Goose, differing 

 chiefly in being much more depressed, and not much more than half 

 the size. The form of the neural arch, however, much more 

 closely resembles that of Colymbus. A narrow, compressed, hori- 

 zontal, transverse platform is given off (fig. 8 d). It is emarginate 

 anteriorly and posteriorly, and directed outward and somewhat back- 



