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Elasmobranchii

Fig. 3.13. Chsracłers of thc Elasmobranchii. A. generał aspect of a Rccent shark (Sgualus-. aboot x0.1); B. sagittal section throagh tbe braincase (section of cattjłage hatched); C. braincase in dorsał view; D. branchial skcleton m dorsal vfew (rtani etements ia biack); E, vcrtkal section throagh a vertcbra wrth calcified centrom (arcuaiia stippled); F. kft nasai openings of Sąuatus ia realni view; G, right orbita] cavity of Squalus. showing the eyę-staik; H. organ tzation of tbe płacoid scales ia tbe $kin of an rlaimohraach. showing the patp cavity ia tbe scalę crown by transpareocy (aboot x20): I. portion of the lower jaw of a shark in labial view, showing the devefoping and functioml teeth. 1. spinele; 2, gili siks; 3, interior fontaneUe; 4, ventral fteaort: 3. eodolymphatic fossa; 6. nasal capsnle; 7. postorbital process; 8, occipital condyles; 9, postótiorly directed hypobranchials: 10, centobrrachfad; łł, tpftnarbal;

12. pharyngobranchial; 13, basibrnncbial copula; 14, bastdotsal; 13. basiventńl; 16, centrom; 17, interior nostril; 18, ponterior ocwtrik 19, skin flap (ala nasal is); 20. eye-stalk; 21. scalę crown; 22, scalę rooc 23, polp cavtty; 24, fuactiooal tooth; 23. dereloping tooth.

(B, C. G, fron Devillen (1938); D, modified front Rosen et al. (1981); E, frótn Goodrich (1930); F, front Marinelti aad Strcnger (1939); H, front 0rvig (19686); I. front Bendia-Alragreen (1983).)