﻿WEALDEN FORMATIONS. 



5 



give the answer to the question, " Whether the cavernous structure of its skeleton was 

 related to pneumatic functions, as in Birds, flying Reptiles, and some others ?' n The 

 central cavity is completely closed ; no pneumatic orifice or canal penetrates thereto : it 

 had no communication with pulmonary or other air-cells. Nor is the alternative limited 

 to marrow. 2 Primitive " chondrine," to which ossification had not extended, most 

 probably filled the vacuity in the vertebral body shown at d, fig. 2, plate ii, of the 

 ' Memoires de la Societe Linneenne de Normandie,' sixieme volume, 4to, 1838; as 

 in figures of Plate I, fig. 3, of the present Supplement, and in fig. 16 of Leidy's plate xv, 

 op. cit. 



Order. DINOSAURIA (?) 



Genus — Chondrosteosaurus. 



Species. Chondrosteosaurus gigas ; Owen. Plates II — V. 



The flatness of the under surface of the vertebra figured in Plates II — V recalled the 

 character of that of Bothriospondglus s?/ffossus, s and, with the predominance of the trans- 

 verse over the vertical diameter, suggested that it also might have come from the sacral 

 series. 



The hemispheroid convexity, however, of the anterior end, notwithstanding abrasion of 

 the articular surface itself, and the proof of its truly indicating such form given by the 

 more perfect preservation of that surface in the opposite concave articular end (Plate III), 

 too plainly pointed to a much more forward position of this remarkable vertebra in the 

 backbone series of the huge Reptile which it represents. 



That the vertebra is from the fore part of the trunk may be inferred from the 

 presence, on each side, of both a parapophysis (PI. II, P ) and a diapophysis (ib., d), 

 indicative of the bifurcation of the proximal end of the rib into a capitular and a 

 tubercular articulating process. 



The portion of neural canal preserved (Plates III and IV, n ) gives the vertical 

 diameter of the centrum. There is no indication in the concave articular surface of that 

 diameter having been diminished by posthumous pressure. The gentle transverse con- 



1 Id., p. 279. 



2 " Dans lea deux series, le corps des vertebres est creuse d'une graude cavite medullaire (fig. 2 d, 

 et v. b) ; le tissu spongieux n'existe qu'aux deux bouts; il y a de chaque cote, dans la gouttiere laterale 

 un trou pour le passage des vaisseaux nonrriciers," p. 78; "ces vertebres presentent a l'interieure une 

 grande cavite medullaire analogue a celle des os longs." Mem. cit., p. 83. 



3 'Monogr. on Brit. Foss. Eeptilia of the Mesozoic Formations,' Part II, PI. Ill, Pal. Soc. vol. for the 

 year 1875. 



