WEALDEN FORMATIONS. 5 



The three vertebrae {he. cit., tab. xix) retain, what is rarely preserved in such 

 complex parts of fossil Saurians, the entire neural spines, ns, and exhibit a disposition 

 and proportions of those parts which have not before been noticed in any Dinosaurian, 

 or in the dorsal vertebrae of any other reptile, recent or fossil. 



That these vertebras are from the fore part of the chest is indicated, according to 

 the analogy of the Crocodilia and of the Iguanodon, by the articular surfaces for both 

 the head and tubercle of the rib, and by the progressive ascent of the surface, p, 

 for the head of the rib, as the vertebrae recede in position. By reference to the 

 T. XIX, in the previous Monograph, loc. cit., it will be seen that this surface 

 slightly projects, and is situated upon the neurapophysial suture in the first, p, ns, but 

 above that suture, supported wholly by the neurapophysis, in the third of those 

 vertebrae, p, ns 1 '. The megalosaurian character of all of the vertebrae is shown by the 

 great, though regular and gradual constriction of the centrum between its articular 

 ends, by the corresponding depth of the concave contour lengthwise, and by the almost 

 circular form of the transverse section of the lower two thirds of the centrum. The 

 non-articular surface of the centrum is smooth and polished, with some longitudinal 

 grooves and ridges near the expanded ends, the bodies of which are thick and rounded. 

 The side of the centrum is moderately hollowed below the neural suture, and swells 

 out, becoming convex vertically, before bending round to the under surface. There 

 is a rough tuberosity, t, at the upper and back part of the centrum, which may be 

 contributed by the base of the neurapophysis. 



The neural arch offers the same complex structure as in other Dinosauria : a com- 

 pressed plate, b, extends obliquely backward from the parapophysis, p, to the diapo- 

 physis, d; the latter being supported by a stronger buttress extending outward from 

 near the back part of the base of the neurapophysis, and being slightly inclined for- 

 ward. Three deep depressions, probably receiving parts of the lungs in the living 

 animal, divide these lamelliform buttresses from each other, and from the bases of the 

 anterior, z, and posterior, z', zygapophyses. The articular surface of the anterior one 

 looks upward and slightly inward, that of the other, -', downward and slightly 

 outward, both being nearly horizontal. The neural platform extends from the outer 

 margin of the prezygapophyses, z , to the fore part of the postzygapophyses, z'. The 

 back part of the base of the neural spine is formed by two strong ridges, continued 

 each from the whole upper part of the postzygapophysis, leaving an intermediate fossa 

 for the implantation of a ligament : the base extends forward to the interspace between 

 the prezygapophyses, being coextensive lengthwise with the vertebral centrum. 



In the anterior of the three vertebrae the spine, ns, as it rises, slightly decreases in 

 fore-and-aft extent, and then as gradually regains its dimension in that direction : after 

 contracting transversely to a thickness of eight lines, when two inches above its 

 base, it gradually expands to a thickness of one inch and a half at its summit, which 

 forms a rough tuberosity, bevelled off obliquely from before upward and backward 



