88 ZOOTOMY. 



below, and (b) caudal vertebrae, with complete inferior 

 arches. 



2. The skull, consisting of {a) the brain-case, formed 

 of a number of bones iirmly united by suture ; (b) a num- 

 ber of more or less loosely attached bones, in relation 

 with the brain-case, and constituting the skeleton of the 

 upper and lower jaws and suspensorium, the hyoidean ap- 

 paratus or tongue-bones, and the gill-covers ; and (ir) the 

 branchial arches or bony framework which supports 

 the gills. 



3. The bones of the median fins, namely, the three 

 dorsal fins, the two anal fins, and the caudal fin 

 (see § 94). 



4. The bones of the pectoral fins, or fore-limbs, and 

 of the shoulder girdle to which they are attached 



(§ 95)- 



5. The bones of the pelvic fins, or hind-limbs, and 

 of the hip-girdle to which they are attached (§ 96). 



III. Examine a vertebra from about the middle of the 

 trunk region, and make out 



6. The centrum or body of the vertebra, a short bony 

 cylinder with deeply concave anterior and posterior ends ; 

 the bi-convex spaces between adjacent centra are filled in the 

 recent state by a gelatinous substance, the remains of the 

 embryonic notochord. 



7. The neural processes, two plates arising vertically 

 one from each side of the upper surface of the centrum, 

 near its anterior end, and uniting with one another to form 

 the neural arch, from the vertex of which the long slender 

 neural spine springs and takes a direction upwards and 

 slightly backwards. From the anterior edge of each neural 

 process a somewhat triangular projection is continued 

 forwards, and answers to the anterior zygapophysis of 



