Elements of the comparative anatomy Elements of the comparative anatomy of vertebrates elementsofcompar00wied Year: 1886 THE SKULL. 61 which the uppermost becomes inserted under the base of the skull, while the lowermost comes to lie ventrally, and is connected with its fellow by a median piece, or basi-branchial (Fig. 45, 1 to 4, (7/7). The two anterior visceral arches also undergo a segmentation. Thus the first becomes divided into a short proximal piece, the quadrate, and into a long distal Meckel's cartilage (Fig. 46, Qu, J/). The quadrate grows out anteriorly into a process, the palatoqu
Elements of the comparative anatomy Elements of the comparative anatomy of vertebrates elementsofcompar00wied Year: 1886 THE SKULL. 61 which the uppermost becomes inserted under the base of the skull, while the lowermost comes to lie ventrally, and is connected with its fellow by a median piece, or basi-branchial (Fig. 45, 1 to 4, (7/7). The two anterior visceral arches also undergo a segmentation. Thus the first becomes divided into a short proximal piece, the quadrate, and into a long distal Meckel's cartilage (Fig. 46, Qu, J/). The quadrate grows out anteriorly into a process, the palatoquadrate or palatopterygoid (Figs. 47 and 48, A to C, PQ), which becomes fixed to the base of the skull, and thus forms a sort of primary upper jaw. The quadrate, which serves as a support (suspensorium) for the lower jaw, either remains separated from the skull by an articu- lation, that is, is only united to it by connective-tissue, or it forms one mass with it. The hyoid arch,—which always stands in close relations to the mandibular, and may also take part in its suspensorial apparatus,1 E C, FIG. 48.—SEMI-DIAGRAMMATIC FIGURES OF THE SUSPENSORIAL APPARATUS IN VARIOUS VERTEBRATES. (Mainly after Gegenbaur.) A, NOTIDANUS'; B, OTHER ELASMOBRANCHS ; C, TORPEDO ; D, TELEOSTEANS ; E, AMPHIBIANS, REPTILES, AND BIRDS ; F, MAMMALS. M, Meckel's cartilage ; PQ, palato-quadrate ; Hm, hyomandibular; ky, hyoid arch ; 8y, symplectic ; Q (in Band E), quadrate ; Q (in F), articular (malleus), and Q1, quadrate (incus), both of which lie in the tympanic cavity (P) ; hl, styloid process, connected with the anterior (lesser) corner of the hyoil (h) by the stylohyoid ligament, indicated by 'the dotted lines ; b, the posterior (greater) cornn, and c, the body of the hyoid in Mammals. -becomes divided, as do the true branchial arches, into a great number of pieces (Fishes), which are distinguished from above downwards as hyomandibular, symplectic, and hyoid in a narrower senselTig. 48, A to D,
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