169 



fore-feet. Cause both internal oblique eye muscles 

 to roll outward, &c., &c. A ^ a^ a^ a'^ a'^. 



a 2 Of ^ Form tlie rear of the composite spine. 

 Cause the back, from the junction of the third and 

 ophidian S S to the tail, to begin forming a con- 

 vex in the medium perpendicular plane*. Increase 

 the outward hearing of both hind-feet. 



sl'^ a'^. Forms the anterior part of the com- 

 posite spine. Moves the neck-root joint as ball and 

 socket for these lines. Increases outward hearing 

 of hoth fore-feet. 



a^ a^. Both digastrics roll outward. Both loops 

 drawn back. Muscles connecting pubis and ster- 

 num tightened. Bicomposite spine formed in rear 

 for anterior Hne. 



a'^ a'^. Fore-feet fully on outward bearing. 

 Digastric loops to rear limits. Motion of con- 

 dyles and motion in neck-root joint completed for 

 anterior lines. Bicomposite spine completed for 

 the same. Both lower jaw articulations set on 

 their analogical outer bearing. 



B B. In the ophidian and composite spines these 



* The perpendicular convexities are properly two for each S S S, 

 but, as the bicomposite spine forms, the various portions are so reduced 

 as to form two for the whole body, one the neck and part of the ophid- 

 ian spine, the other, jiart of the ophidian spine and the third S. Be- 

 tween the two the centre of the ophidian spine lies in concave. 



