WEALDEN FORMATIONS. 35 



Of the nature of the sacrum and pelvis in the present genus nothing definite 

 and assured is at present known. Such proportions of the entire skeleton of one and 

 the same individual as have imparted our present knowledge of the Iguanudon 

 and Megalosaur, have not yet been discovered of the Cetiosaurus. Certain co- 

 existences in relation to strata and localities, but hardly amounting to juxtaposition, 

 indicated that the tibia and some other limb-bones of the Reptile with Cetiosaurian 

 vertebrse were without a medullary cavity, and with the centre occupied by a coarse 

 cancellous tissue.* 



At the period when the vertebrae of this type were first discriminated from the 

 veritable ones of the Iguanodon, I had not met with this characteristic structure of 

 Cetiosaurian limb-bones in strata above the Portland Stone (Middle Oolite). They 

 have since been found in the Wealden strata. 



The late Dr. Man tell, in his Memoir on the Pelorosaurus, states : "I have a series 

 of bones from Brook, in the Isle of Wight, through the kindness of my distinguished 

 friend. Sir R. 1. Murchison, proving the existence of Cetiosauri in the Wealden ; 

 all the long bones are destitute of a medullary cavity."! 



A somewhat crushed femur of Cetiosaurus longus, measuring 4 feet 3 inches 

 in length, from the Middle OoUte at Enslow Bridge, Oxfordshire, is preserved 

 in the Geological Museum at Oxford : it does not show any medullary cavity. The 

 specimens of Cetiosaurian long bones, from Wealden strata, which have hitherto 

 come under my observation, are fragmentary. It is probable that parts of the coracoid 

 and pubic bones, also from the Wealden, indicating a greater relative breadth of those 

 elements of scapular and pelvic arches, than in true Orocodilia, but differing in form 

 from the answerable bones in known Dinosauria, may have belonged to Cetiosaurus 

 brevis, Ow. 



The suppression of the species so named by me has been proposed, and its 

 appropriation by another has been attempted,! under the name of Cetiosaurus 

 Conybeari, Melville, " in order to prevent confusion and to remove the objection 

 that may well be raised against the nomen triviale ' brevis ;' " " for w^ho will venture," 

 asks the appropriator, " to indicate the relative length of an animal with no known 

 affine, from four of its anterior caudal vertebrae?" 



Believing that the generic affinity of the Cetiosaurus brevis with Cetiosaurus longus 

 and Cetiosaurus medius to have been demonstrated, I ventured to suggest, in 1841, 

 that the nomen triviale might be found appropriate in reference to the relative length 

 of the entire body, from what was then known " of the constancy and regularity 

 of this dimension" (viz., length of vertebral centrum) "in the back bone of 



* 'Report on BritUli Fossil Reptiles,' 1S41, p. 102. 

 t ' Pliilosophical Transactions,' 1850, p. 381. 

 X Ibid., 184f), p. 297. 



