A treatise on zoology . cartilage at the top of the hyoid arch ; but from the evidenceof embrvologv and the course of the hvomandibular branch of the SKULL 171 fiiciiil nerve, it would uppear more probable that the hyomandibularis indistinguishably fused l)oth with the auditory capsule and withthe quadrate, the spiracle being suppressed (Fig. 135). If thisinterpretation is correct, the autostylism of the Holocephali differs1 adically from that of the Dipnoi, and has probably been derivedfrom a hyostylic structure. Cartilaginous branchial rays arepresent in single series, as in the Selachii (p.
A treatise on zoology . cartilage at the top of the hyoid arch ; but from the evidenceof embrvologv and the course of the hvomandibular branch of the SKULL 171 fiiciiil nerve, it would uppear more probable that the hyomandibularis indistinguishably fused l)oth with the auditory capsule and withthe quadrate, the spiracle being suppressed (Fig. 135). If thisinterpretation is correct, the autostylism of the Holocephali differs1 adically from that of the Dipnoi, and has probably been derivedfrom a hyostylic structure. Cartilaginous branchial rays arepresent in single series, as in the Selachii (p. 123), and are muchdeveloped on the hyoid arch to supi)ort the operculum (Fig. 134).One of the most characteristic organs of the Holocephali is the. ^ eh. cbr gp. Fic. Callorhyiwhas antarcticus, Lac. A, skeleton ami nerves of tlie liead of a young specimen(after Schauinslands figures), an, auilitory capsule ; h, buccal branch of facial nerve ; cbr, 5thceratobranchial ; ch, ceratohyal; dr, dorsal median rostral cartilage; eh, epihyal; yp, glosso-pharynseal nerve ; mk, Meckels cartilage ; j), palato-quadrate region ; jjA, pharyngoliyal; q,quadrate, or probably hyomandibular, region ; 6-, interorbital septum ; sp, spinal nerve-roots ;vb, vi, vl, branchial, intestinal, and lateral-line brandies of vagus nerve ; , ventral pairedrostral cartilage ; 2, optic, 3, oculomotor, 4, pathetic, 5, trigeminal, 6, abducent, and 7, facialnerves. B, calcified skeletal supports of the lateral line. frontal clasper, or tenaculum, found in all undoubted members ofthe group from the Jurassic time onwards, but in the male sexonly. It is a movable median process, supported by a cartilaginousaxis articulated to the skull above and in front of the
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Keywords: ., bookcentury1900, bookdecade1900, bookpublishe, booksubjectzoology
