68 PHYSIOLOGICAL SERIES. 



of fibrous tissue. The biconical space enclosed between 

 each pair of vertebral bodies is filled with a gelatinous 

 material that represents the remains of the notochord. 



The articulation of the bodies with each other is rendered 

 more rigid by an overlapping of processes on the bodies 

 by corresponding projections of the neural arch and 

 transverse processes of the succeeding vertebra. 



An anterior view of a vertebra is shown above ; below, 

 11 vertebrae (the first 5 of which are in sagittal section) are 

 seen from the left side. 



Scheel, Morph. Jahrb., Bd. xx. 1893, p. 1. 



B. 90. The caudal extremity of the vertebral column of Lepido- 

 siren paradoxa seen from the left side. In this and in the 

 other Dipnoi the notochord is obliterated towards the end 

 of the tail and replaced by a number of rectangular blocks 

 of cartilage, each surmounted by a variable number of 

 arcualia. They probably do not represent vertebral bodies. 

 Klaatseh, Morph. Jahrb., Bd. xx. 1893, p. 151. 



B. 91. A longitudinal and vertical section of two vertebrae of a 

 Siren (Siren lacertind}. The articular surfaces of the 

 bodies of the vertebra are hollowed out as in fish, but 

 the cavities are occupied by ligamentous fibres disposed 

 in concentric circles : the articular processes are joined 

 by capsular and synovial membranes. 0. C. 246. 



Hunter ian. 

 Mivart, Proc. Zool. Soc. 1870, p. 260. 



B. 92. A longitudinal and vertical section of the cervical vertebrse 

 of a Turtle (Clielone mydas), the bodies of which are 

 connected by ligamentous substance passing between the 

 whole of their articular surfaces. 



These surfaces, in the first, second, and third vertebrse, 

 are convex at the anterior part, and concave at the posterior; 

 in the fourth they are convex at both ends; the anterior 

 surface of the fifth is concave, the posterior plane ; both 

 surfaces are plane in the sixth ; but the posterior surface 

 of the seventh vertebra is convex. 0. C. 248. Hunterian. 



