40 



ANATOMY OF VERTEBRATES. 



developed. The interlocking process of the anterior vertebra dis- 

 appears as the true inferior transverse process is increased. The 

 side of the neural arch is perforated for the nerve, and that of the 

 haemal arch for the blood-vessel. The anterior abdominal vertebra 



3 , of the Tetrodon are 



firmly clamped to- 

 gether by the para- 

 pophyses. 



A vegetative same- 

 ness of form prevails 

 in fishes throughout 

 the vertebral column 

 of the trunk, fig. 34, 

 which is made up of 

 only two kinds of ver- 

 tebras, characterised 

 by the direction of 

 the parapophyses, p : 

 these in the abdomi- 

 nal region are lateral, 

 usually stand out and 

 support ribs : but in 

 the caudal region 

 bend down to form, 

 either by direct co- 

 alescence or by the 

 ribs that continue to 

 be attached to them 

 in a vertical position, 

 the hremal arch. 



The atlas is usu- 

 ally distinguished by 

 some modification of 

 the anterior articular 

 end of the centrum, 

 by the persistent 

 suture of the neural 

 arch, or by the ab- 

 sence or detachment 

 of its pleurapophy- 

 ses. Peculiar pro- 

 cesses are sometimes 



Skeleton of the Haddock (Gadus cegleflnus) SCnt off from the 



