1905.] 



DINOSAUR CETIOSAURUS LEEDSI. 



237 



continuous series of 27 vertebrae, of which only some of the 

 foremost are defective in preservation. The first of these middle 

 caudals is the most imperfect, and its neural spine is hypo- 

 thetically fixed ; but the centrum is shown to be sharply rounded 

 below, with a distinctly double facette for the chevron behind. 

 All these vertebras are much more elongated than the anterior 

 caudals, and somewhat laterally compressed ; but they are still 

 slightly constricted, without any la^teral pits, while both their 

 articular ends are a little concave. As they are traced backwards, 

 the centra not only decreasa in size but soon lose the l.ist remnant 

 of a transverse process ; while their neural spines become shorter. 



Text-fig. 42. 



Cetiosaurus leedsi. — ^Anteinor caudal vertebra ; posterior and (A) rig-lit lateral 

 aspects. j)z., postzvgapophysis ; tr., transverse process ; zs., zygosplieiie. 

 [Brit. Mus. no. 11. 1984.] About ^ nat. size. 



broader, and thinner, and more sharply inclined towards imbrica- 

 tion. The seventh vertebra of this series (text-fig. 43) is especially 

 well preserved. The anterior face of its centrum (text-fig. 43 A) is 

 relatively broader than its postei'ior face (text-fig. 43 B), and the 

 transverse process is a mere ovate tubercle (tr.) on the middle of 

 the upper part of its side. The neural spine scarcely overhangs 

 the centrum behind, and its truncated upper end is still slightly 

 hollowed. The prezygapophyses {az.) are large and clasping, but 

 the postzygapophyses {j^z.) are feeble, and there is no zygosphene- 

 articulation. A large opening is left for the exit of the spinal 



