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FOSSIL REPTILIA OF THE 



characters of the sacrum will be subsequently discussed. But the demonstration of the 

 sacral characters of a more recently discovered Cetiosauroid genus, the subject of 

 another Monograph in the present volume, adds to the grounds for referring the type- 

 species to the great Dinosaurian group of Reptilia. 



It is characteristic of the accidents that attend the quest and acquisition of the 

 remains of extinct Vertebrates, that skull, jaws, and teeth should have escaped the careful 

 operations to which we are indebted for the present means of restoring both Cetiosaurus 

 longus and Omosaurus armatus. Of the former reptile a single doubtful and mutilated 

 tooth was all that Prof. Phillips could refer with any degree of probability to that 

 species. 



That the side-pits of saurian vertebrae have no essential relation to largely cancellated, 

 pseudo-pneumatic structure of the bones is shown by their presence in the anterior 

 trunk-vertebrae of the genus for which the uniformly close though coarse osseous texture, 

 as in the whale tribe, suggested the generic name Cetiosaurus. 



The first indication of this type of Saurian was, however, afforded by an inspection 

 of a limb-bone, submitted tome by Dr. Buckland in 1838, when I was engaged in 

 collecting materials for my ' Report ' to the British Association " On the Fossil Reptilia 

 of Great Britain." Buckland had referred to this fossil in his ' Bridgewater Treatise,' 

 1st edit., 1836, in the following terms: — "There is in the Oxford Museum an ulna 

 from the Great Oolite of Enstone " (Enslow probably meant), " near Woodstock, Oxon., 

 which was examined by Cuvier and pronounced to be cetaceous ; and also a portion of 

 a very large rib, apparently of a whale, from the same locality." 



This limb-bone I could not match with any then known to me in the Cetaceous order. 

 Yet, save a thin compact outer crust, the osseous structure was, where exposed, like that 

 in the humerus of a Whale or Grampus; there was no medullary cavity. In shape the 

 resemblance, though remote, seemed nearest to that of the outer metatarsal of a 

 Monitor Lizard. 1 



Shortly after I was able to differentiate certain saurian vertebrae from those ascribed 

 to the genera Iguanodon, Hylceosaurus, Megalosaurus, and Poikilopleuron, not only by 

 superiority of size, but by differences in form, proportions, and structure. 2 The latter 

 character applied, more especially, to these huge unknown fossil bones in the comparison 

 with Poikilopleuron, in the vertebrae of which four-footed reptile ossification is incom- 

 plete and large chondrosal vacuities are left in the substance of the centrum, which, in 

 the fossils, become filled with spar. 3 



1 See ' Monograph on a Fossil Dinosaur (Scelidosaurus) of the Lower Lias,' tab. xi, fig. 3 v ; 

 Palseontographical Society's volume for 1860. Prof. Phillips, who had obtained, in 1870, from the Great 

 Oolite at Enslow, the three metatarsals of each hind foot of a Cetiosaurus, wherewith he was able to com- 

 pare the above fossil long bone, " incomplete at both extremities," considers the determination of it as a 

 metatarsal of large size to be 'probably true.' — 1 Geology of Oxford,' &c, 8vo, 1871, p. 285. 



2 'Proceedings of the Geological Society of London,' June, 1841, loc. cit. 



3 The chief of these cavities, being in the centre of the vertebrae, was termed 'medullary' (loc. cit., 



