;J26 



Vurlnlirnki. 



'Vhv iLNinl Hkcli'Iriiii, ('.(■., iiliG i'ii(l(i-Hl<('l('ldii of llii' IkmIv willi 

 the exclii.41011 of tliiil/ of lilm liinbH, will now Iki iMiiiHiddinMl, In huimo 

 I'MhIk'h II, coul.iimoiiH oa rt i 1 M gi H (Ml 8 slieiirtli iii'ihch rdimd ihv 

 cliordii ill tlie t^niiik luid hi,il nijj'iiniH; ilii.H Mdic Ih rinHiMl iirhove hy n, 

 series ol' short tHicUlorni pionuH, in' iiruli (^H, whit^li Hiii'fomid l-ho spinal 

 cord. I n hkimI. Vortohridiii, Mio (•iii'l-ilii^'inons hIioiUiIi is, howovnr, dividiid 

 into ii, iiunibor of ])i(H'nH, imiiiiJIy (uio I'dr cim'Ii iu'cIi, ii.nd IJiohi' l-ojj'i'Mu'r 

 surround tlic nDioclmi'd. TIh^ho picH'os, which iiro tornicd ciMitris 

 differ consiihu'iiJily in form ii.iid strnoinro ; Honiolinuw tho euolosod 

 notoohord persists 1,f) n f^roiiit (vxtont, in olilior cii.hoh it is voi'y de- 

 generate or vnuishoH ahnost ciimpU^tnly. A ciud.rnin, tof/oUior with its 

 arch, is tc^rinod a vertohra; iircli iind ceiitrutn aw usually Hrndy 

 nnil.cMl and consist of ciM'l.ilag'd or lione. In Llio 

 region <ir Mio tail nnindrdim inl'oi'ior arolins 

 aro fiJ/l,acli(ul fo the cdnira, tlidy rc^sinnhle the 

 Huporior lU'clioH, and enc^dso Uk^ large cii.iidal 

 vessel. Fforn iJid vertelirid, various pfoccHHOH 

 arisd ; abdvd, from i^i\.i:]\ n.rcli, ii, nun rid Hpino; 

 latorally, transverse processes, arlicuilar processes 

 willi ii.rtic-nliiT TiwotH, wliic.li lid ufioii those of 

 succeeding vdrtdbi'io, and hooii rilis ii.ro id,tacluMl 

 to most df the trunk vertdlirin, excepting i/lm 

 luitorior and pdHf,(iridr on(^M, one pair l.o (lacli 

 vertohni/. 'I'lioy are cartilaginous or liony rods 



Fi(f. 260. 1)111- -wliic}! Herve ii.s a Hiiptidri, td i.lio hody-wnJl ; in the 

 gram of a v o r t o - ' •' 



bra find Wio parts nighc^r Vorl-dhni.tii, tlicy ii.rc pii.rl.ly (^onnociod (icldw 

 coimootod with it. ]^y ,^ sternnni, an niipiurcd, imiially partially 

 or cotnplctdly osHifiod cii.rtilii.gc, Hil,iiid,od in tlio 



r-h notoohord, h coti- 

 tmm, b nonrttl arch, 

 / neural Bpine, m 

 Bpinal cord, r rili, 

 br utomnm. — ^Orijf. 



body-wall; it is absent from I'^IhIi, ami ttiongli 

 present in ATnpliihiii,, is not cdTindctcd with the 

 ribs. In liigiior Vorifsbrn.ta (Reptiliii., Avok, 

 Mammalia, and to somo cxl.cnt even in llic jAmpliibiii,), the scrii^s ol' 

 trunk vortobrii; may bo (]ivid(;d inf.o KcvornJ rotrionH ; 1. corvic, a I 

 vortebric, with or wiUiout smidl ribs ; 2. thoracic vorlfcbrjc, 

 with well-developed ribw; '■>. lumbar vertebric, Kiieec^eding the 

 thoracicH, with no i-ibs ; 4. sac nil vert, ebrie, t.o wliirli the 

 pelvis is att.ardiod. 'riiene regi<;Tis cirtinot b(! diHhini/iiiKlied iu I'iseeK, 

 where the trunk via't^ebrfe ;i,re usually all similiir. 



The primitive cephalic Hkcleton Ik h. strong enpHuli!, the 

 cranium, enclosing tlie brsuri, protecting jiJho the ojjtic and 

 olfactory organw, whilst the Jiuditory ii,[ipanitiiK in imbedded in its 

 walls, JtH ventral wall ih continuous with the vertebne, and 

 suiTounds the anterior end of the notocliord — a very degenerate 

 structure in the adult. In the embryo the cranium ih entirely 

 cartilagiridUH, and this Ih occasionally the cane in thf; adult ii.lso, 

 though a certain amount of fibrous tinHiio is prenent, filling in the 



