330 Proceedings of the British Association. 



and-socket articulation of the vertebrce, but with the position re- 

 versed, to which the name Streptospondylus has been given by 

 Von Meyer. It has been found in the has near Whitby, and the 

 oolite near Chipping Norton. Prof. Owen next proceeded to de- 

 scribe the remains of some gigantic Saurians, ranging from the 

 greensand to the oolite, and which rivalling the modern whales in 

 bulk, may be presumed to have been of strictly aquatic, and prob- 

 ably of marine habits. They have the biconcave structure of the 

 vertebrse, and the long bones show no trace of a medullary cavity. 

 Of the first of these, named by Prof. Owen, Cetiosaiirus, (de- 

 scribed in report of Proc. Geol. Soc.) the vertebra and other bones, 

 found in the lower oolite of Chipping Norton, belonged probably 

 to an individual forty feet in length. Prof O. has assigned to 

 mis species the name of C. hypoolithicus ; and to another species 

 the name of C. epioolithicus, remains of which, including a ver- 

 tebra eight inches in length of body, and nine inches in trans- 

 verse diameter, occurs in the Yorkshire oolite at White Nab. 

 The ninth section of the Report was devoted to the description 

 of a large marine Saurian, teeth of which were frequent in the 

 chalk of Barnwell, and in Sussex, in the Folkstone gait, and the 

 lower greensand near Maidstone. From the structure of the 

 teeth, Prof O. had assigned to it in his "Odontography," the 

 name of Polyptychodo?i. Several bones of a gigantic Saurian, dis- 

 covered by Mr. Mackeson in the greensand quarries near Hythe, 

 were considered as probably belonging to the same genus. Of 

 the genus Mosasaurus, only a few vertebras have been found in 

 the English chalk formation. Teeth, resembling those of the 

 Mosasaurus, but differing in the elliptic form of the base of the 

 crown in a transverse section, have been found in the chalk of 

 Norfolk, and were described by the generic appellation, Leiodon. 

 The report next proceeded to the account of the extinct species, 

 which manifested, in the enduring parts of their organization, an 

 intimate relationship with the numerous and varied tribes of the 

 smaller and lower organized Saurians of the present epoch, to 

 which the term Lacertians or Squamate Saiiria were applied. 

 Prof O. observed that in this, as in the foregoing divisions of the 

 Saurian order, the ancient world possessed very singular and also 

 very gigantic species, which have now utterly perished, and have 

 given place to carnivorous and herbivorous quadrupeds of more 

 active habits and higher organization. The first fossils noticed, 



