70 PHYSIOLOGICAL SERIES. 



show the intervertebral fibrous band. A green rod and 

 black bristles have been inserted in different places between 

 it and the intervertebral disc. 



B. 100. A longitudinal horizontal section of two cervical verte- 

 brae of an Ostrich (Struthio camelus), exposing the cavity of 

 the joint which unites these vertebrae ; here, the anterior 

 surface is convex, the posterior concave. 0. C. 251. 



Hunterian. 



B. 101. A longitudinal vertical section of two anterior dorsal 

 vertebrae of the Ostrich, the bodies of which are articulated 

 by a capsular ligament, as in the preceding specimen; the 

 articular surfaces are saddle-shaped, with the two faces in 

 reversed positions. The canal for the passage of the 

 medulla spinalis is enlarged near the articulation, to prevent 

 its being compressed in the motions of that part of the spine. 

 0. C. 252. Hunterian. 



B. 102. Vertebra of Tachyylossus [Echidna"] aculeata, and left 

 halves of two others, showing the intervertebral substance, 

 and its central cavity. 0. C. 246 A. 



B. 103. A transverse section of the intervertebral substance of the 

 Bottlenose Whale (Hyperoodon rostrata). 



It is 153 mm. in diameter ; the external 13 mm. appears 

 of uniform consistency, and exhibits very little of the fibrous 

 character. The rest of the substance, to within 16 rnm. of 

 the centre, is composed of ligamentous fibres arranged in 

 concentric circles, and at nearly equal distances; the 

 remaining central part appears to be wholly occupied by 

 glairy matter. 0. C. 245. Hunterian. 



Hunter, On the Whale, Phil. Trans., vol. Ixxvii. 1781, 

 tab. xix. 



B. 104. A longitudinal section of two caudal vertebrae of a Horse 

 (Equus caballus) . These vertebrae form a remarkable con- 

 trast to those of fishes, as they present to each other convex, 

 instead of concave, surfaces. 0. C. 242. Hunterian. 



