32 



ANATOMY OF VERTEBRATES. 



layer of the notochordal capsule has assumed the texture of tough 

 hyaline cartilage; and not only are firm opake cartilagmous 

 neurapophyses "present, but also parapophyses, pleurapophyses, 



fibro-aiiliroso 

 CMual 



neural canal 

 gclatlniius chorda 



c=a( 



inner l-iyei" I'f 

 niiruUH capsule as 

 hyaline cartilage 



ncurapopnysis 

 internenral cartilage 



plcurapopliysis 



j>arainipliysis 

 iiiterliLeraal cartiiag 



hanial canal 

 Abjonlina! vertebra, Sturgemi 



Fore part ef skeleton. Lamprey trdwmiizon) 



and neural spines. The part of the neurapophysis Ijounding the 

 true neural canal is usually distinct from that l^ounding the fat- 

 filled fissure aljove. The parapophyses are united by a con- 

 tinuous phvtc of cartilage forming an inverted arch beneath the 



aorta, in the truidv, ana- 

 logous to that formed by 

 bone in the lower neck- 

 vertebra3 of birds, fig. 20. 

 In the Ch'uiKxra slen- 

 der subossified rinss 

 appear in the cartilagi- 

 nous sheath of the noto- 

 cliord, ■svhich are more 

 numerous than the neu- 

 ral arches. These, where unconfluent with each other, are 

 distinct also from the parajiophyses, which in the tail bend 

 down to form the hasmal arches. In the INIeditcrranean Grey 

 Shark (Nofiduniis cinerens) the vertebral centres arc still feebly 

 and irrelatively marked out by numerous slender rings of hard 

 cartilage in the notochordal capsule, the uumljer of vertebra? being 

 more definitely indicated by the neurapophyses and i^arapophyses ; 

 but these remain cartilaginous. 



In the Lepidosiren the peripheral vertebral elements, fig. 41, n, 

 nx, p, hs, arc ossified, but the notochord, eh, with a thicker and 

 condensed capsule, remains. In the Piked Dog-fisli {Acaiitliiof:) 

 the vertebral centres coincide in number with tlic neural arches, 

 and are defined by a thin plate of bone, sliajicd like an hour- 

 glass, and fornnng the conical cavity at eacli end of the centrum : 

 the rest of whieli is cartilaginous external to the ' lionr-^Iass," and 

 sul)gelatinous within its terminal cavities. In the 8[iotted Dog- 

 fisli {Sri/Uiiiiii) the two thin bony cones of each centrum are con- 



