90 ZOOTOMY. 



foramina ; they serve for the transmission of the spinal 

 nerves. 



13. The ribs, slender, flattened bones, articulated to the 

 distal ends of the transverse processes and curving outwards 

 and downwards. 



14. The inter-muscular bones, shorter and slenderer 

 than the ribs, but otherwise resembling them : they are articu- 

 lated one to each transverse process on its dorsal side 

 and a short distance from its distal end, and curve upwards 

 and outwards. 



V. In the caudal vertebrae note 



15. The haemal arch, formed by the union in the 

 middle ventral line of two haemal processes, springing one 

 from each side of the ventral surface of the centrum near 

 its anterior end ; from the point of union a haemal spine is 

 given off and passes downwards and backwards. The 

 haemal processes give rise to anterior zygapophyses like those 

 on the neural arches, and similarly articulating with small 

 processes from the centrum of the vertebra next in front. 



1 6. In the anterior caudal region the haemal are very much 

 larger than the neural arches, but passing back the former 

 diminish progressively until there is no difference of import- 

 ance, either in the size of the arches or the length of 

 the spines, between the neural and haemal aspects of the 

 vertebrae. 



17. Following the last undoubted caudal vertebra is the 

 small fan-shaped hypural bone, which together with the 

 somewhat flattened posterior neural and haemal spines 

 supports the tail-fin. 



VI. In the median fins make out 



18. The interspinous bones of the dorsal and anal 

 fins, alternating with the neural and haemal spines respec- 

 tively, and attached to them by fibrous tissue. 



